1285 and Level 5

Level 5 puzzles can be tricky if you don’t carefully pick where you start, but you’re not going to let that discourage you, are you?

Print the puzzles or type the solution in this excel file: 10-factors-1281-1288

Here are a few facts about the number 1285:

  • 1285 is a composite number.
  • Prime factorization: 1285 = 5 × 257
  • The exponents in the prime factorization are 1 and 1. Adding one to each and multiplying we get (1 + 1)(1 + 1) = 2 × 2 = 4. Therefore 1285 has exactly 4 factors.
  • Factors of 1285: 1, 5, 257, 1285
  • Factor pairs: 1285 = 1 × 1285 or 5 × 257
  • 1285 has no square factors that allow its square root to be simplified. √1285 ≈ 35.8469

5(2⁸ + 1) = 1285. Look at the digits on both sides of that equation. They are the reason that 1285 is the 20th Friedman number.

1285 is the sum of three consecutive prime numbers:
421 + 431 + 433 = 1285

1285 is the sum of two squares two different ways:
33² + 14² = 1285
31² + 18² = 1285

1285 is the hypotenuse of FOUR Pythagorean triples:
160-1275-1285 which is 5 times (32-255-257)
637-1116-1285 calculated from 31² – 18², 2(31)(18), 31² + 18²
771-1028-1285 which is (3-4-5) times 257
893-924-1285 calculated from 33² – 14², 2(33)(14), 33² + 14²

1284 and level 4

Ten clues are in this puzzle. Two of them are 9’s and two of them are 10’s, but that doesn’t cause any problems, . . . .probably!

Print the puzzles or type the solution in this excel file: 10-factors-1281-1288

Here are some facts about the number 1284:

  • 1284 is a composite number.
  • Prime factorization: 1284 = 2 × 2 × 3 × 107, which can be written 1284 = 2² × 3 × 107
  • The exponents in the prime factorization are 2, 1, and 1. Adding one to each and multiplying we get (2 + 1)(1 + 1)(1 + 1) = 3 × 2 × 2 = 12. Therefore 1284 has exactly 12 factors.
  • Factors of 1284: 1, 2, 3, 4, 6, 12, 107, 214, 321, 428, 642, 1284
  • Factor pairs: 1284 = 1 × 1284, 2 × 642, 3 × 428, 4 × 321, 6 × 214, or 12 × 107
  • Taking the factor pair with the largest square number factor, we get √1284 = (√4)(√321) = 2√321 ≈ 35.83295

1284 is the sum of twin primes: 641 + 643 = 1284

1283 and Level 3

What is the greatest common factor of 28 and 63? If you know, then you can probably figure out this puzzle!

Print the puzzles or type the solution in this excel file: 10-factors-1281-1288

Here are some facts about the number 1283:

  • 1283 is a prime number.
  • Prime factorization: 1283 is prime.
  • The exponent of prime number 1283 is 1. Adding 1 to that exponent we get (1 + 1) = 2. Therefore 1283 has exactly 2 factors.
  • Factors of 1283: 1, 1283
  • Factor pairs: 1283 = 1 × 1283
  • 1283 has no square factors that allow its square root to be simplified. √1283 ≈ 35.81899

How do we know that 1283 is a prime number? If 1283 were not a prime number, then it would be divisible by at least one prime number less than or equal to √1283 ≈ 35.8. Since 1283 cannot be divided evenly by 2, 3, 5, 7, 11, 13, 17, 19, 23, 29 or 31, we know that 1283 is a prime number.

1283 is the sum of the seventeen prime numbers from 41 to 109,
AND it is the sum of the thirteen primes from 71 to 131.

1282 and Level 2

Can you find the factors from 1 to 10 that make the twelve clues in the puzzle the correct products for this scrambled multiplication table?

Print the puzzles or type the solution in this excel file: 10-factors-1281-1288

Here is some information about the number 1282:

  • 1282 is a composite number.
  • Prime factorization: 1282 = 2 × 641
  • The exponents in the prime factorization are 1 and 1. Adding one to each and multiplying we get (1 + 1)(1 + 1) = 2 × 2 = 4. Therefore 1282 has exactly 4 factors.
  • Factors of 1282: 1, 2, 641, 1282
  • Factor pairs: 1282 = 1 × 1282 or 2 × 641
  • 1282 has no square factors that allow its square root to be simplified. √1282 ≈ 35.80503

1282 is the sum of two squares:
29² +  21² = 1282

1282 is the hypotenuse of a primitive Pythagorean triple:
400-1218-1282 calculated from 29² –  21², 2(29)( 21), 29² +  21²

The 21, 29, and 400 above are related to another Pythagorean triple:
20-21-29 because 20² = 400, 21² = 441 and 29² = 841. Thus,
400 + 441 = 841. Pretty cool!

1281 and Level 1

Can you write the numbers from 1 to 10 in the top row and the first column so that the given clues will make this puzzle work like a multiplication table? That’s how you solve the puzzle!

Print the puzzles or type the solution in this excel file: 10-factors-1281-1288

Now I’ll write a little bit about the number 1281:

  • 1281 is a composite number.
  • Prime factorization: 1281 = 3 × 7 × 61
  • The exponents in the prime factorization are 1, 1, and 1. Adding one to each and multiplying we get (1 + 1)(1 + 1)(1 + 1) = 2 × 2 × 2 = 8. Therefore 1281 has exactly 8 factors.
  • Factors of 1281: 1, 3, 7, 21, 61, 183, 427, 1281
  • Factor pairs: 1281 = 1 × 1281, 3 × 427, 7 × 183, or 21 × 61
  • 1281 has no square factors that allow its square root to be simplified. √1281 ≈ 35.79106

1281 is also the sum of consecutive prime numbers in two different ways:
167 + 173 + 179 + 181 + 191 + 193 + 197 = 1281
241 + 251 + 257 + 263 + 269 = 1281

1281 is the hypotenuse of a Pythagorean triple:
231-1260-1281 which is 21 times (11-60-61)

1280 and Level 6

To me, today’s level 6 puzzle looks a little like a puppy dog. If you know or use a multiplication table, then with proper training, finding the factors of this puzzle will be no problem.

Print the puzzles or type the solution in this excel file: 12 factors 1271-1280

I’d like to tell you a little about the number 1280:

  • 1280 is a composite number.
  • Prime factorization: 1280 = 2 × 2 × 2 × 2 × 2 × 2 × 2 × 2 × 5, which can be written 1280 = 2⁸ × 5
  • The exponents in the prime factorization are 8 and 1. Adding one to each and multiplying we get (8 + 1)(1 + 1) = 9 × 2 = 18. Therefore 1280 has exactly 18 factors.
  • Factors of 1280: 1, 2, 4, 5, 8, 10, 16, 20, 32, 40, 64, 80, 128, 160, 256, 320, 640, 1280
  • Factor pairs: 1280 = 1 × 1280, 2 × 640, 4 × 320, 5 × 256, 8 × 160, 10 × 128, 16 × 80, 20 × 64, or 32 × 40
  • Taking the factor pair with the largest square number factor, we get √1280 = (√256)(√5) = 16√5 ≈ 35.77709.

1280 is the sum of the fourteen prime numbers from 61 to 127. Do you know what those prime numbers are?

32² + 16² = 1280

1280 is the hypotenuse of a Pythagorean triple:
768-1024-1280 which is (3-4-5) times 256
That triple can also be calculated from 32² – 16², 2(32)(16), 32² + 16²

Since 1280 is the 5th multiple of 256, I would expect that a number close to 1280 would be the 500th number whose square root could be simplified. That number was 1275, just five numbers ago.

1279 and Level 5

Can you find the factors for the one and only solution to this puzzle that will make the clues be the products of those factors? Sure you can! Give it a try, and don’t give up no matter what!

Print the puzzles or type the solution in this excel file: 12 factors 1271-1280

Now I’ll write a little about the number 1279:

  • 1279 is a prime number.
  • Prime factorization: 1279 is prime.
  • The exponent of prime number 1279 is 1. Adding 1 to that exponent we get (1 + 1) = 2. Therefore 1279 has exactly 2 factors.
  • Factors of 1279: 1, 1279
  • Factor pairs: 1279 = 1 × 1279
  • 1279 has no square factors that allow its square root to be simplified. √1279 ≈ 35.76311

How do we know that 1279 is a prime number? If 1279 were not a prime number, then it would be divisible by at least one prime number less than or equal to √1279 ≈ 35.7. Since 1279 cannot be divided evenly by 2, 3, 5, 7, 11, 13, 17, 19, 23, 29 or 31, we know that 1279 is a prime number.

1279 is a prime number that helps us find another VERY big prime number. As OEIS.org informs us, 2¹²⁷⁹ – 1 is also a prime number and is known as a Mersenne Prime.

 

1278 and Level 4

Try your hand at solving this level 4 puzzle. Your ability to do so might just surprise you!

Print the puzzles or type the solution in this excel file: 12 factors 1271-1280

Since this is my 1278th post, I’ll write a little bit about that number:

  • 1278 is a composite number.
  • Prime factorization: 1278 = 2 × 3 × 3 × 71, which can be written 1278 = 2 × 3² × 71
  • The exponents in the prime factorization are 1, 2, and 1. Adding one to each and multiplying we get (1 + 1)(2 + 1)(1 + 1) = 2 × 3 × 2 = 12. Therefore 1278 has exactly 12 factors.
  • Factors of 1278: 1, 2, 3, 6, 9, 18, 71, 142, 213, 426, 639, 1278
  • Factor pairs: 1278 = 1 × 1278, 2 × 639, 3 × 426, 6 × 213, 9 × 142, or 18 × 71,
  • Taking the factor pair with the largest square number factor, we get √1278 = (√9)(√142) = 3√142 ≈ 35.74913

1278 and the four numbers immediately preceding it are the smallest consecutive numbers for which 4 of the 5 numbers each have exactly 12 factors.

1278 is the sum of eight consecutive prime numbers:
139 + 149 + 151 + 157 + 163 + 167 + 173 + 179 = 1278

 

 

1277 Strată Bolyai János in Timișoara, Romania

Around the turn of the 20th century, Bolyai Farkás taught mathematics at a university in Transylvania.  One day he was too sick to teach, so he sent his mathematically gifted 13-year-old son, János, to teach his classes! As you might imagine, János became quite the mathematician in his own right.

Ninety-five years ago today Bolyai János went to Timișoara, Romania to announce his findings concerning geometry’s fifth postulate. For centuries it was argued that this parallel lines postulate could probably be proved using the previous four of Euclid’s postulates, and it should, therefore, be considered a theorem rather than a postulate. Bolyai János proved that it is indeed something that must be assumed rather than proven, because, by assuming it wasn’t necessary, he was able to create a new and very much non-Euclidean geometry, now known as hyperbolic geometry or Bolyai–Lobachevskian geometry.

Last summer I was walking with some family members through a shopping area behind the opera house in Timișoara, Romania. Suddenly my son, David, excitedly shouted, “Mom, look!” There we stood in front of a street sign marking the strată named for Bolyai János! Here is a picture of me in front of that street sign.

Under his image are several plaques. The first is a replica of part of his proof. Underneath are plaques with a quote from him translated into several languages. Perhaps your favorite language is among them. Here is a close-up of the plaques:

The plaque at the bottom is in English, “From nothing I have created a new and another world. It was with these words that on November 3, 1823, Janos Bolyai announced from Timișoara the discovery of the fundamental formula of the first non-Euclidean geometry.”

We did not get to visit the university named for Bolyai János, but I am thrilled that my son spotted this historic location!

Now I’ll write a little about the number 1277:

  • 1277 is a prime number.
  • Prime factorization: 1277 is prime.
  • The exponent of prime number 1277 is 1. Adding 1 to that exponent we get (1 + 1) = 2. Therefore 1277 has exactly 2 factors.
  • Factors of 1277: 1, 1277
  • Factor pairs: 1277 = 1 × 1277
  • 1277 has no square factors that allow its square root to be simplified. √1277 ≈ 35.73514

How do we know that 1277 is a prime number? If 1277 were not a prime number, then it would be divisible by at least one prime number less than or equal to √1277 ≈ 35.7. Since 1277 cannot be divided evenly by 2, 3, 5, 7, 11, 13, 17, 19, 23, 29 or 31, we know that 1277 is a prime number.

1277 is the sum of two squares:
34² + 11² = 1277

1277 is the hypotenuse of a Pythagorean triple:
748-1035-1277 calculated from 2(34)(11), 34² – 11², 34² + 11²

Here’s another way we know that 1277 is a prime number: Since its last two digits divided by 4 leave a remainder of 1, and 34² + 11² = 1277 with 34 and 11 having no common prime factors, 1277 will be prime unless it is divisible by a prime number Pythagorean triple hypotenuse less than or equal to √1277 ≈ 35.7. Since 1277 is not divisible by 5, 13, 17, or 29, we know that 1277 is a prime number.

1276 is the Third Number in a Row with Exactly 12 Factors

1276 is the 125th number to have exactly 12 factors. I’ve made a list of those numbers in the graphic below. Two consecutive numbers appearing on the list have only happened three times before. Those numbers are highlighted in blue. 1276 is special because with it, for the first time THREE consecutive numbers appear on the list!

Look at the prime factorizations of those three consecutive numbers:
1274 = 2·7²·13
1275 = 3·5²·17
1276 = 2²·11·29

How are they the same? Can you figure out a reason why they all have exactly 12 factors?

By the way, prime number 1277 spoiled the streak especially since 1278 = 2·3²·71 and also has 12 factors!

If you came up with a rule, I think you should know that not all numbers with 12 factors will follow that same rule. For example,
2³·3² = 72 and has 12 factors because 4·3=12.
2⁵·3 = 96 and has 12 factors because 6·2 = 12.

I hope that strengthens your hypothesis instead of destroying it!

Now I’ll tell you some more facts about the number 1276:

  • 1276 is a composite number.
  • Prime factorization: 1276 = 2 × 2 × 11 × 29, which can be written 1276 = 2² × 11 × 29
  • The exponents in the prime factorization are 2, 1, and 1. Adding one to each and multiplying we get (2 + 1)(1 + 1)(1 + 1) = 3 × 2 × 2 = 12. Therefore 1276 has exactly 12 factors.
  • Factors of 1276: 1, 2, 4, 11, 22, 29, 44, 58, 116, 319, 638, 1276
  • Factor pairs: 1276 = 1 × 1276, 2 × 638, 4 × 319, 11 × 116 22 × 58, or 29 × 44
  • Taking the factor pair with the largest square number factor, we get √1276 = (√4)(√319) = 2√319 ≈ 35.72114

1276 is the sum of 12 consecutive prime numbers:
79 + 83 + 89 + 97 + 101 + 103 + 107 + 109 + 113 + 127 + 131 + 137 = 1276

1276 is the hypotenuse of a Pythagorean triple:
880-924-1276 which is (20-21-29) times 44

Finally, from OEIS.org, we learn that 1276 = 1111 + 22 + 77 + 66.