947 and Level 4

If you know how to multiply and divide, then you can solve this puzzle. Just use logic to find the factors from 1 to 12 that go in the first column and the top row. Go ahead give it a try!

Print the puzzles or type the solution in this excel file: 12 factors 942-950

Now here’s a little about the number 947:

947 is a prime number that can be written as the sum of seven consecutive prime numbers:
113 + 127 + 131 + 137 + 139 + 149 + 151 = 947

947 is a palindrome in three other bases:
3B3 BASE 16 (B is 11 base 10), because 3(16²) + 11(16¹) + 3(16⁰) = 947
232 BASE 21 because 2(21²) + 3(21¹) + 2(21⁰) = 947
1L1 BASE 22 (L is 21 BASE 10), because 1(22²) + 21(22¹) + 1(22⁰) = 947

  • 947 is a prime number.
  • Prime factorization: 947 is prime.
  • The exponent of prime number 947 is 1. Adding 1 to that exponent we get (1 + 1) = 2. Therefore 947 has exactly 2 factors.
  • Factors of 947: 1, 947
  • Factor pairs: 947 = 1 × 947
  • 947 has no square factors that allow its square root to be simplified. √947 ≈ 30.773365

How do we know that 947 is a prime number? If 947 were not a prime number, then it would be divisible by at least one prime number less than or equal to √947 ≈ 30.8. Since 947 cannot be divided evenly by 2, 3, 5, 7, 11, 13, 17, 19, 23, or 29, we know that 947 is a prime number.

What Kind of Shape Is 946 In?

First of all, 946 is the sum of the numbers from 1 to 43, so it is the 43rd triangular number.

Every other triangular number is also a hexagonal number. Since 946 is the 43rd triangular number, and 43 is an odd number, 946 is also the 22nd hexagonal number. 946 is the 22nd hexagonal number because 22(2(22) – 1) = 22(43) = 946.

But that’s not all. 946 is different than any previous hexagonal number. 946 is the smallest hexagonal number that is also a hexagonal pyramidal number. It is, in fact, the 11th hexagonal pyramidal number. That means if you stack the hexagons in the graphic below in order from largest to smallest, you would get a hexagonal pyramid made with 946 tiny squares. That’s pretty cool, I think.

 

467 + 479 = 946 so 946 is the sum of two consecutive prime numbers.
946 is also the sum of the twenty prime numbers from 11 to 89.

946 is palindrome 181 in BASE 27 because
1(27²) + 8(27¹) + 1(27⁰) = 729 + 216 + 1 = 946

  • 946 is a composite number.
  • Prime factorization: 946 = 2 × 11 × 43
  • 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 946 has exactly 8 factors.
  • Factors of 946: 1, 2, 11, 22, 43, 86, 473, 946
  • Factor pairs: 946 = 1 × 946, 2 × 473, 11 × 86, or 22 × 43
  • 946 has no square factors that allow its square root to be simplified. √946 ≈ 30.75711

There’s Something Odd about the Number 945

945 = 1 × 3 × 5 × 7 × 9

The sum of the proper divisors of a number determines if the number is abundant, deficient, or perfect. If the sum is greater than the number, the number is abundant. If the sum is less than the number, the number is deficient. If the sum is equal to the number, the number is perfect.

What is a proper divisor? All the factors of a number except itself. Proper divisors are ALMOST the same thing as proper factors. (The number 1 is always a proper divisor, but NEVER a proper factor.)

The first 25 abundant numbers are 12, 18, 20, 24, 30, 36, 40, 42, 48, 54, 56, 60, 66, 70, 72, 78, 80, 84, 88, 90, 96, 100, 102, 104, and 108. Notice that all those numbers are even.

OEIS informs us that 945 is the 232nd abundant number. The first 231 abundant numbers are all even numbers.

Wow, 945 is the smallest ODD abundant number. OEIS also lists the first 31 odd abundant numbers. Every one of the first 31 is divisible by 3 and ends with a 5, but if you scroll down the page you’ll see some that aren’t divisible by 3 or aren’t divisible by 5.

Since 1 × 3 × 5 × 7 × 9 = 945 is the smallest number on the list, you may be wondering about some other numbers:
1 × 3 × 5 × 7 × 9 × 11 = 10,395 made the list.
1 × 3 × 5 × 7 × 9 × 11 × 13 = 135,135 which is too big to be one of the first 31 odd abundant numbers. I was curious if it is also an abundant number, so I found its proper divisors and added them up:

945 is also the hypotenuse of a Pythagorean triple:
567-756-945 which is (3-4-5) times 189

945 looks interesting in a few other bases:
1661 in BASE 8 because 1(8³) + 6(8²) + 6(8¹) + 1(8⁰) = 945
RR in BASE 34 (R is 27 base 10), because 27(34¹) + 27(34⁰) = 27(35) = 945
R0 in BASE 35 because 27(35) + 0(1) = 945

  • 945 is a composite number.
  • Prime factorization: 945 = 3 × 3 × 3 × 5 × 7, which can be written 945 = 3³ × 5 × 7
  • The exponents in the prime factorization are 3, 1, and 1. Adding one to each and multiplying we get (3 + 1)(1 + 1)(1 + 1) = 4 × 2 × 2 = 16. Therefore 945 has exactly 16 factors.
  • Factors of 945: 1, 3, 5, 7, 9, 15, 21, 27, 35, 45, 63, 105, 135, 189, 315, 945
  • Factor pairs: 945 = 1 × 945, 3 × 315, 5 × 189, 7 × 135, 9 × 105, 15 × 63, 21 × 45, or 27 × 35
  • Taking the factor pair with the largest square number factor, we get √945 = (√9)(√105) = 3√105 ≈ 30.74085

944 and Level 3

The division facts needed to solve today’s puzzle are not complicated. You can fill in all the cells of this puzzle if you know the multiplication facts from 1 × 1 to 12 × 12.

Print the puzzles or type the solution in this excel file: 12 factors 942-950

Now here are some facts about the number 944:

944 is divisible by 2 because it is even.
944 is divisible by 4 because the last number is divisible by 4 and the digit before it is even.
944 can be evenly divided by 8 because 44 is divisible by 4, but not by 8, and the digit before 44 is odd.

944 is a funny-looking palindrome, 1I1, in BASE 23 (I is 18 in base 10) because 1(23²) + 18(23¹) + 1(23⁰) = 944

  • 944 is a composite number.
  • Prime factorization: 944 = 2 × 2 × 2 × 2 × 59, which can be written 944 = 2⁴ × 59
  • The exponents in the prime factorization are 4 and 1. Adding one to each and multiplying we get (4 + 1)(1 + 1) = 5 × 2 = 10. Therefore 944 has exactly 10 factors.
  • Factors of 944: 1, 2, 4, 8, 16, 59, 118, 236, 472, 944
  • Factor pairs: 944 = 1 × 944, 2 × 472, 4 × 236, 8 × 118, or 16 × 59
  • Taking the factor pair with the largest square number factor, we get √944 = (√16)(√59) = 4√59 ≈ 30.72458

943 and Level 2

Level 2 puzzles aren’t very tricky, but maybe this one is a little bit. Can you write the factors from 1 to 12 in both the first column and the top row so that this puzzle functions as a multiplication table?

Print the puzzles or type the solution in this excel file: 12 factors 942-950

Now I’ll write something about the number 943:

943 is the hypotenuse of a Pythagorean triple:
207-920-943 which is 23 times (9-40-41)

It is also a leg in two primitive Pythagorean triples:
576-943-1105, calculated from 2(32)(9), 32² – 9², 32² + 9²
943-444624-444625, calculated from 472² – 471², 2(472)(471), 472² + 471²

  • 943 is a composite number.
  • Prime factorization: 943 = 23 × 41
  • 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 943 has exactly 4 factors.
  • Factors of 943: 1, 23, 41, 943
  • Factor pairs: 943 = 1 × 943 or 23 × 41
  • 943 has no square factors that allow its square root to be simplified. √943 ≈ 30.708305

942 and Level 1

This puzzle is probably as tough as a level 1 puzzle can get, but don’t let that prevent you from giving it a try! Can you figure out where the factors from 1 to 12 go in both the first column and the top row?

Print the puzzles or type the solution on this excel file: 12 factors 942-950

Now let me tell you a little about the number 942:

It is the sum of four consecutive prime numbers:
229 + 233 + 239 + 241 = 942

It is the hypotenuse of a Pythagorean triple:
510-792-942 which is 6 times (85-132-157)

942 is a palindrome in two other bases and a repdigit in another:
787 in BASE 11, because 7(11²) + 8(11¹) + 7(11⁰) = 942
272 in BASE 20, because 2(20²) + 7(20¹) + 2(20⁰) = 942
666 in BASE 12, because 6(12²) + 6(12¹) + 6(12⁰) = 6(144+12+1) = 6(157) = 942

942³ is 835,896,888. OEIS.org tells us that 942³ is the smallest perfect cube that contains five 8‘s.

  • 942 is a composite number.
  • Prime factorization: 942 = 2 × 3 × 157
  • 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 942 has exactly 8 factors.
  • Factors of 942: 1, 2, 3, 6, 157, 314, 471, 942
  • Factor pairs: 942 = 1 × 942, 2 × 471, 3 × 314, or 6 × 157
  • 942 has no square factors that allow its square root to be simplified. √942 ≈ 30.6920185

940 Mystery Level

Today’s puzzle reminds me of a gumball machine. I would invite you to stick to solving this puzzle until you find success. I assure you that the factors from 1 to 10 can be placed in the first column and the top row solely by using logic.

Print the puzzles or type the solution on this excel file: 10-factors-932-941

Now let me tell you something about the number 940.

940 is the hypotenuse of a Pythagorean triple:
564-752-940 which is (3-4-5) times 188

  • 940 is a composite number.
  • Prime factorization: 940 = 2 × 2 × 5 × 47, which can be written 940 = 2² × 5 × 47
  • 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 940 has exactly 12 factors.
  • Factors of 940: 1, 2, 4, 5, 10, 20, 47, 94, 188, 235, 470, 940
  • Factor pairs: 940 = 1 × 940, 2 × 470, 4 × 235, 5 × 188, 10 × 94, or 20 × 47,
  • Taking the factor pair with the largest square number factor, we get √940 = (√4)(√235) = 2√235 ≈ 30.659419

Is There Anything Else Special about the Palindrome 939?

Yes, 939 is a palindrome in base 10, but also all of its factors (1, 3, 313, and 939) are palindromes. It is also palindrome
32223 in BASE 4 because 3(4⁴) + 2(4³) + 2(4²) + 2(4¹) + 3(4⁰) = 939

Okay, that’s nice. Is there anything else special about 939?

The first ten decimal places of the cube root of 939 contain ALL ten digits 0 to 9. That’s unusual, and a reason why 939 is a special number. I made this gif to highlight its uniqueness.
Cube Root 939

make science GIFs like this at MakeaGif

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Thank you OEIS.org for informing us of that amazing fact about 939’s cube root.

939 is also the hypotenuse of a Pythagorean triple:
75-936-939 which is 3 times (25-312-313)

  • 939 is a composite number.
  • Prime factorization: 939 = 3 × 313
  • 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 939 has exactly 4 factors.
  • Factors of 939: 1, 3, 313, 939
  • Factor pairs: 939 = 1 × 939 or 3 × 313
  • 939 has no square factors that allow its square root to be simplified. √939 ≈ 30.64310689

 

938 and Level 5

Can you figure out where the factors 1 – 10 go in the first column and top row so that this level 5 puzzle will function as a multiplication table?

Print the puzzles or type the solution on this excel file: 10-factors-932-941

Now I’ll share a few facts about the number 938.

938 is a palindrome in two consecutive bases:
It’s 343 in BASE 17 because 3(17²) + 4(17¹) + 3(17º) = 938
It’s 2G2 in BASE 18 (G is 16 base 10), because 2(18²) + 16(18¹) + 2(18º) = 938

  • 938 is a composite number.
  • Prime factorization: 938 = 2 × 7 × 67
  • 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 938 has exactly 8 factors.
  • Factors of 938: 1, 2, 7, 14, 67, 134, 469, 938
  • Factor pairs: 938 = 1 × 938, 2 × 469, 7 × 134, or 14 × 67
  • 938 has no square factors that allow its square root to be simplified. √938 ≈ 30.62678566

935 Is the Second Lucas-Carmichael Number

935 = 5 × 11 × 17, and 935 + 1 is evenly divisible by 5 + 1, 11 + 1, and 17 + 1. That makes 935 only the SECOND Lucas-Carmichael number. Thanks to OEIS.org for that fun fact.

Today’s puzzle is a level 3, a good transition from the easier puzzles to the more difficult ones.

Print the puzzles or type the solution on this excel file: 10-factors-932-941

Here’s more about the number 935:

935 is the sum of the nineteen prime numbers from 13 to 89.

935 is the hypotenuse of four Pythagorean triples:
143-924-935, which is 11 times (13-84-85)
396-847-935, which is 11 times (36-77-85)
440-825-935, which is (8-15-17) times 55
561-748-935, which is (3-4-5) times 187

  • 935 is a composite number.
  • Prime factorization: 935 = 5 × 11 × 17
  • 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 935 has exactly 8 factors.
  • Factors of 935: 1, 5, 11, 17, 55, 85, 187, 935
  • Factor pairs: 935 = 1 × 935, 5 × 187, 11 × 85, or 17 × 55
  • 935 has no square factors that allow its square root to be simplified. √935 ≈ 30.5777697