Puzzle

Both17 and 34 are Factors of 1734 and Help It Make Sum-Difference

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Today’s Puzzle:

1734 has only 6 factor pairs, but two of those pairs will solve a Sum-Difference puzzle.

Let’s start with the first puzzle below. Can you find a factor pair of 6 that adds up to 5 and another one that subtracts to 5? If you can, then you have solved the first puzzle. The second puzzle is really just a multiple of the first puzzle. 5 × what = 85? Multiply the numbers you write in the first puzzle by that same number, and you will have the numbers needed to solve the second puzzle. You can also look at the factor pairs in the next section to help you find the needed factors that sum or subtract to 85.

Factors of 1734:

Because 17×2=34, their concatenation, 1734, is divisible by three. All of the following concatenated numbers are also divisible by three: 12, 24, 36, 48, 510, 612, 714, 816, 918, 1020, 1122, 1224, 1326, 1428, 1530, 1632, 1734, 1836, 1938, and so forth.

  • 1734 is a composite number.
  • Prime factorization: 1734 = 2 × 3 × 17 × 17, which can be written 1734 = 2 × 3 × 17².
  • 1734 has at least one exponent greater than 1 in its prime factorization so √1734 can be simplified. Taking the factor pair from the factor pair table below with the largest square number factor, we get √1734 = (√289)(√6) = 17√6.
  • The exponents in the prime factorization are 1, 1, and 2. Adding one to each exponent and multiplying we get (1 + 1)(1 + 1)(2 + 1) = 2 × 2 × 3 = 12. Therefore 1734 has exactly 12 factors.
  • The factors of 1734 are outlined with their factor pair partners in the graphic below.

More About the Number 1734:

Did you notice that both 17 and 34 are factors of 1734?

From OEIS.org we learn that 1734 has three factors that have 8 as one of their digits, 867, 578, and 289. What do you get when you add those factors together?

1734 is the hypotenuse of two Pythagorean triples:
816-1530-1734, which is (8-15-17) times 102. and
966-1440-1734, which is 6 times (161-240-289).

1734 looks interesting in some other bases:
It’s 600 in base 17 because 6(17²) = 1734, and
it’s 369 in base 23 because 3(23²) + 6(23) + 9(1) = 1734.

What is the greatest common factor of 1734 and 2023? What is the least common multiple? The easiest way to know is to look at their prime factorizations.
1734 = 2·3·17²,
2023 = 7·17².
The greatest common factor is what they have in common: 17² = 289.
The least common multiple is 2·3·7·17² = 12138.

1732 Is a Thousand Times More Than…

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Today’s Puzzle:

If you know the common factor of 50 and 35 that will put only numbers from 1 to 12 in the first column and the top row of this multiplication table puzzle, then you will have completed the first step in solving the puzzle. Afterward, just work from the top of the puzzle to the bottom filling in factors as you go. That’s how you solve these level-three puzzles.

Factors of 1732:

  • 1732 is a composite number.
  • Prime factorization: 1732 = 2 × 2 × 433, which can be written 1732 = 2² × 433.
  • 1732 has at least one exponent greater than 1 in its prime factorization so √1732 can be simplified. Taking the factor pair from the factor pair table below with the largest square number factor, we get √1732 = (√4)(√433) = 2√433.
  • The exponents in the prime factorization are 2 and 1. Adding one to each exponent and multiplying we get (2 + 1)(1 + 1) = 3 × 2 = 6. Therefore 1732 has exactly 6 factors.
  • The factors of 1732 are outlined with their factor pair partners in the graphic below.

More About the Number 1732:

1732 is the sum of two squares:
34² + 24² = 1732.

1732 is the hypotenuse of a Pythagorean triple:
580-1632-1732, calculated from 34² – 24², 2(34)(24), 34² + 24².
It is also 4 times (145-408-433).

1732 is a palindrome in base 15 because
7(15²) + 10(15) + 7(1) = 1732.

I remember one of my college professors telling his class that
√2 is about 1.4, and Valentine’s day is February 14,
√3 is about 1.7, and Saint Patrick’s day is March 17.

That’s how I remember those values, but this tweet reminded me that 1732 is a thousand times more than the square root of three rounded to three decimal places. It also makes a reference to the square root of two.

1731: The Sum of the Squares of Three Consecutive Prime Numbers

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Today’s Puzzle:

Write the numbers from 1 to 12 in both the first column and the top row so that the given clues are the products of the numbers you write.

Factors of 1731:

  • 1731 is a composite number.
  • Prime factorization: 1731 = 3 × 577.
  • 1731 has no exponents greater than 1 in its prime factorization, so √1731 cannot be simplified.
  • The exponents in the prime factorization are 1 and 1. Adding one to each exponent and multiplying we get (1 + 1)(1 + 1) = 2 × 2 = 4. Therefore 1731 has exactly 4 factors.
  • The factors of 1731 are outlined with their factor pair partners in the graphic below.

More About the Number 1731:

1731 is the hypotenuse of a Pythagorean triple:
144-1725-1731 which is 3 times (48-575-577).

OEIS.org informs us that 1731 is the sum of the squares of three consecutive prime numbers. Let’s find those three prime numbers. Since √(1731/3) rounds to 24, I’m guessing the middle prime number is 23. The prime numbers occurring before and after it are 19 and 29.

Is 19² + 23² + 29² = 1731? Yes, it is!

Here are some other ways that 1731 is the sum of three squares:
41² + 7² + 1² = 1731,
41² + 5² + 5² = 1731,
37² + 19² + 1² = 1731, and
29² + 29² + 7² = 1731.

How Is 1730 the Sum of Consecutive Squares?

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Today’s Puzzle:

Write all the numbers from 1 to 12 in both the first column and the top row so that those numbers are the factors of the given clues.

Factors of 1730:

  • 1730 is a composite number.
  • Prime factorization: 1730 = 2 × 5 × 173.
  • 1730 has no exponents greater than 1 in its prime factorization, so √1730 cannot be simplified.
  • The exponents in the prime factorization are 1, 1, and 1. Adding one to each exponent and multiplying we get (1 + 1)(1 + 1)(1 + 1) = 2 × 2 × 2 = 8. Therefore 1730 has exactly 8 factors.
  • The factors of 1730 are outlined with their factor pair partners in the graphic below.

More about the number 1730:

1730 is the sum of two squares in two different ways:
41² + 7² = 1730, and
37² + 19² = 1730.

1730 is the hypotenuse of FOUR Pythagorean triples:
520 1650 1730 which is 10 times (52-165-173)
574 1632 1730 calculated from 2(41)( 7), 41² – 7², 41² + 7²,
1008 1406 1730 calculated from 37² – 19², 2(37)(19), 37² + 19², and
1038 1384 1730 which is 346 times (3-4-5).

Finally, OEIS.org informs us that 1730 is the sum of consecutive squares in two different ways. What are those two ways? I figured it out. Can you?

Here’s a hint: It is the sum of three consecutive squares as well as twelve consecutive squares. That means √(1730/3) rounded is included in one sum and √(1730/12) rounded is included in the other. The solution can be found in the comments. Have fun finding them yourself though!

1729 Not a Dull Number

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Today’s Puzzle:

A little more than a hundred years ago near Cambridge University G. H. Hardy took a taxi to visit his young friend and fellow mathematician, Srinivasa Ramanujan, in the hospital. Hardy couldn’t think of anything interesting about his taxi number, 1729, and remarked to Ramanujan that it appeared to be a rather dull number. But even the reason for his hospitalization could not prevent Ramanujan’s genius from shining through. He immediately recognized 1729’s unique and very interesting attribute: it is the SMALLEST number that can be written as the sum of two cubes in two different ways! Indeed,
12³ + 1³ = 1729, and
10³ + 9³ = 1729.

Today’s puzzle looks a little bit like a modern-day American taxi cab with the clues 17 and 29 at the top of the cab. The table below the puzzle contains all the Pythagorean triples with hypotenuses less than 100 sorted by legs and by hypotenuses. Use the table and logic to write the missing sides of the triangles in the puzzle. The right angle on each triangle is the only one that is marked. Obviously, none of the triangles are drawn to scale.

Sorted TriplesHere’s the same puzzle without all the added color:

Print the puzzles or type the solutions in this excel file: 10 Factors 1721-1729.

What taxi cab might Hardy have tried to catch next? He might have had to wait a long time for it, 4104.
16³ + 2³ = 4104, and
15³ + 9³ = 4104.

Factors of 1729:

  • 1729 is a composite number.
  • Prime factorization: 1729 = 7 × 13 × 19.
  • 1729 has no exponents greater than 1 in its prime factorization, so √1729 cannot be simplified.
  • The exponents in the prime factorization are 1, 1, and 1. Adding one to each exponent and multiplying we get (1 + 1)(1 + 1)(1 + 1) = 2 × 2 × 2 = 8. Therefore 1729 has exactly 8 factors.
  • The factors of 1729 are outlined with their factor pair partners in the graphic below.

More About the Number 1729:

Did you notice these cool-looking factor pairs?
19 · 91 = 1729.
13 · 133 = 1729.

1729 is the hypotenuse of a Pythagorean triple:
665-1596-1729 which is 133 times (5-12-13).

1729 is the difference of two squares in four different ways:
865² – 864² = 1729,
127² – 120² = 1729,
73² – 60² = 1729, and
55² – 36² = 1729.

1728 Is a Perfect Cube

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Today’s Puzzle:

I think this puzzle is a little bit harder than the previous two puzzles, so you might want to solve those two first. You will need to write all the numbers from 1 to 24 where the factors go, but keep the numbers from 1 to 12 together and the numbers from 13 to 24 together. There is only one solution. The possible factors are written to the right of the puzzle. Good luck!

You can solve the puzzle by eliminating factors that must be used for other numbers. For example, 198 cannot be 9×22 because 189 must be 9×21, and the puzzle can only have one nine. Don’t write the factors on the multiplication table until after you know if the top row has the numbers 1 – 12 or if it has the numbers 13 – 24. The first column will then have the other set of numbers.

Factors of 1728:

Let’s find out the factoring information of the puzzle number:

  • 1728 is a composite number and a perfect cube.
  • Prime factorization: 1728 = 2 × 2 × 2 × 2 × 2 × 2 × 3 × 3 × 3, which can be written 1728 = 2⁶ × 3³.
  • 1728 has at least one exponent greater than 1 in its prime factorization so √1728 can be simplified. Taking the factor pair from the factor pair table below with the largest square number factor, we get √1728 = (√576)(√3) = 24√3.
  • The exponents in the prime factorization are 6 and 3. Adding one to each exponent and multiplying we get (6 + 1)(3 + 1) = 7 × 4 = 28. Therefore 1728 has exactly 28 factors.
  • The factors of 1728 are outlined with their factor pairs in the graphic below.

More About the Number 1728:

1728 is the 3rd smallest number with exactly 28 factors.

There are 1728 cubic inches in one cubic foot.

12³₁₀ = 10³₁₂ (The cube above is 12 cubed in base 10, and it’s 10 cubed in base 12.)

1728 can be written as the sum of powers in some interesting ways:

2¹⁰ + 2⁹ + 2⁷ + 2⁶ = 1024 + 512 + 128 + 64 = 1728.
1(4⁵) + 2(4⁴) + 3(4³) = 1728.
1(6⁴) + 2(6³) = 1728.
3(8³) + 3(8²) = 3(8³ + 8²) = 1728.

11³ = 1331, and 1(11³) + 3(11²) + 3(11¹) + 1(11⁰) = 1728.

Here’s another connection with the number 11.
3(11²) = 363, and
1728 is palindrome 363 in base 23 because
3(23²) + 6(23¹) + 3(23⁰) = 1728.

1728 is 300 in base 24 because 3(24²) = 1728.

I’ve enjoyed researching the number 1728, and I hope you’ve learned some new and interesting fact about it today.

1726 Find the Factors 1-12 AND 13-24

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Today’s Puzzle:

Here’s a puzzle I made to start off 2023. Either all the numbers from 1 to 12 will go in the top row OR they will all go in the first column. All the numbers from 13 to 24 will go in the remaining area. The possible factors are written on the side of the puzzle. Can you find all the factors? There is only one solution.

Factors of 1726:

  • 1726 is a composite number.
  • Prime factorization: 1726 = 2 × 863.
  • 1726 has no exponents greater than 1 in its prime factorization, so √1726 cannot be simplified.
  • The exponents in the prime factorization are 1 and 1. Adding one to each exponent and multiplying we get (1 + 1)(1 + 1) = 2 × 2 = 4. Therefore 1726 has exactly 4 factors.
  • The factors of 1726 are outlined with their factor pair partners in the graphic below.

More About the Number 1726:

1726 is the sum of four consecutive numbers from 430 to 433.

1725 A Toast to You on This Last Day of the Year

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Today’s Puzzle:

I haven’t posted as much this past year as I ought, but thank you for bearing with me. Here is a toast to you, faithful reader! Here’s hoping for a great new year for all of us! Write the numbers from 1 to 10 in both the first column and the top row so that the given clues are the products of the factors you write.

Factors of 1725:

  • 1725 is a composite number.
  • Prime factorization: 1725 = 3 × 5 × 5 × 23, which can be written 1725 = 3 × 5² × 23.
  • 1725 has at least one exponent greater than 1 in its prime factorization so √1725 can be simplified. Taking the factor pair from the factor pair table below with the largest square number factor, we get √1725 = (√25)(√69) = 5√69.
  • The exponents in the prime factorization are 1, 2, and 1. Adding one to each exponent and multiplying we get (1 + 1)(2 + 1)(1 + 1) = 2 × 3 × 2 = 12. Therefore 1725 has exactly 12 factors.
  • The factors of 1725 are outlined with their factor pair partners in the graphic below.

More About the Number 1725:

1725 is the difference of two squares in six different ways:

863² – 862² = 1725,
289² – 286² = 1725,
175² – 170² = 1725,
65² – 50² = 1725,
49² – 26² = 1725, and
47² – 22² = 1725.

 

Facts, Factors, and a Countdown to 2023

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Countdown to 2023:

The last 10 seconds of the year, we like to countdown from 10 to the new year. I like a mathematical way of counting down so I try to make an equation with the numbers from 10 to 1 that equals the coming year. This year I could have based my countdown  on last year’s countdown and said
(10-9+8×7×6)(5-4)(3)(2)+1 = 2023,
but this is a blog about factoring so I want a countdown that takes you to the prime factors of 2023 first. Here’s my countdown: (Note: Even though I used 1 as a factor twice in the countdown, I am very much aware that 1 is not a prime factor of any number.)

Countdown to 2023

make science GIFs like this at MakeaGif
Here’s the final shot from the Countdown:

A Puzzle for 2023:

2023 has something in common with 2022. When either number and their reverses are squared, something interesting happens…it’s almost like looking in a mirror!

Only 50 numbers less than 10000 can make a similar claim to fame:

Factors of 2023:

  • 2023 is a composite number.
  • Prime factorization: 2023 = 7 × 17 × 17, which can be written 2023 = 7 × 17².
  • 2023 has at least one exponent greater than 1 in its prime factorization so √2023 can be simplified. Taking the factor pair from the factor pair table below with the largest square number factor, we get √2023 = (√289)(√7) = 17√7.
  • The exponents in the prime factorization are 1 and 2. Adding one to each exponent and multiplying we get (1 + 1)(2 + 1) = 2 × 3 = 6. Therefore 2023 has exactly 6 factors.
  • The factors of 2023 are outlined with their factor pair partners in the graphic below.

More About the Number 2023:

What do 2023 tiny squares look like?

2023 is the sum of consecutive numbers in five different ways:

And it is the sum of consecutive odd numbers in two ways:

2023 is a palindrome in base 16 because
7(16²) + 14(16) + 7(1) = 2023.

This tweet demonstrates that the prime factors of 2023 have a relationship with the digits of 2023.

I saw this tweet on Twitter and immediately recognized something else cool about 2023.

That might seem like a lot of mathematical mumble jumble, but with a little bit of explanation, it can be understood. And even though I made the problem look scarier because I substituted 2+0+2+3 for 7, some older elementary students who already understand powers, factorials, and/or remainders, will get it. I’m confident you can too.

You could also give the following list of facts to older elementary students and ask them to use it to find the remainder when they divide 823,543 by 5040.

1×5040 =    5040
2×5040 = 10080
3×5040 = 15120
4×5040 = 20160
5×5040 = 25200
6×5040 = 30240
7×5040 = 35280
8×5040 = 40320
9×5040 = 45360

Because its factors, 17 and 289, are hypotenuses of Pythagorean triples, 2023 is also the hypotenuse of some Pythagorean triples:
952-1785-2023 which is 119(8-15-17) , and
1127-1680-2023 which is 7(161-240-289).

Ureczky József also pointed out in the comments of this post, that 2023 is the short leg in SIX Pythagorean triples, and thus
2023² = 2046265² – 2046264²
2023²= 292327² – 292320²
2023² = 120377² – 120360²
2023² = 17255² – 17136²
2023² = 41785² – 41736²
2023² = 7225² – 6936²

One of those triples is a primitive triple. Can you determine which one?

Ureczky József shared one more amazing fact in the comments that I’m replicating here:

2023=9³+8³+7³+6³+5³+4³+3³+2³-1³

More Mathematical Tweets About 2023:

These tweets are more or less in the order I saw them, not in order of mathematical difficulty. I will add more as I see them.


v

1724 Carol of the Ukrainian Bells

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Today’s Puzzle:

As I sit in my warm, peaceful house, I often think about the people of Ukraine whose country has been ravaged by war. Many of them, including children, are also facing a winter with no heat. My heart goes out to them.

My childhood was so unlike theirs. I was able to attend school classes and learn about many different topics without fear of dying. In Junior High School choir class, one of the songs I learned was called Carol of the Bells. I just recently learned from Slate magazine of the song’s Ukrainian roots:

A little over a hundred years ago Mykola Leontovych, a Ukrainian composer, arranged several of his country’s folk songs together in a piece he titled Shchedryk. Tragically, he was murdered by a Russian assassin on January 23, 1921, in the Red Terror, when the Bolsheviks were intent on eliminating Ukrainian leaders, intellectuals, and clergy.

During this time of great unrest, the Ukrainian National Chorus performed Shchedryk around the world and in cities large and small in the United States. One performance was even given at the famed Carnegie Hall on October 5, 1922. The haunting melody was heard by Peter Wilhousky who penned alternate words for it: Hark how the bells, Sweet silver bells,…

Now it is one of our most beloved Christmas carols. I am grateful I learned the words and tune in junior high, although I wish I had learned of its Ukrainian history then as well.

These two bells puzzles are reminiscent of Ukraine’s flag. Long may it wave. Write each number 1 to 10 in the yellow columns and rows so that the given clues are the products of the numbers you write.

Here are the same puzzles if you prefer to use less of your printer ink.

Factors of 1724:

  • 1724 is a composite number.
  • Prime factorization: 1724 = 2 × 2 × 431, which can be written 1724 = 2² × 431.
  • 1724 has at least one exponent greater than 1 in its prime factorization so √1724 can be simplified. Taking the factor pair from the factor pair table below with the largest square number factor, we get √1724 = (√4)(√431) = 2√431.
  • The exponents in the prime factorization are 2 and 1. Adding one to each exponent and multiplying we get (2 + 1)(1 + 1) = 3 × 2 = 6. Therefore 1724 has exactly 6 factors.
  • The factors of 1724 are outlined with their factor pair partners in the graphic below.

More About the Number 1724:

1724 is the difference of two squares:
432² – 430² = 1724.

1724₁₀ = 464₂₀, a palindrome, because
4(20²) + 6(20¹) + 4(20°) = 1724.