196 and Level 4

  • 196 is a composite number.
  • Prime factorization: 196 = 2 × 2 × 7 × 7, which can be written 196 = 2² × 7²
  • The exponents in the prime factorization are 2 and 2. Adding one to each and multiplying we get (2 + 1)(2 + 1) = 3 × 3 = 9. Therefore 196 has exactly 9 factors.
  • Factors of 196: 1, 2, 4, 7, 14, 28, 49, 98, 196
  • Factor pairs: 196 =  1 × 196, 2 × 98, 4 × 49, 7 × 28, or 14 × 14
  • 196 is a perfect square. √196 = 14

13 and 14 squared

2014-08-07

Excel file of puzzles and previous week’s factor solutions: 10 Factors 2014-08-04

2014-31 Level 4 Logic

189 and Level 4

189 is a composite number.
Factor pairs: 189 = 1 x 189, 3 x 63, 7 x 27, 9 x 21
Factors of 189: 1, 3, 7, 9, 21, 27, 63, 189
Prime factorization: 189 = 3 x 3 x 3 x 7, which can also be written 189 = (3^3) x 7

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2014-30 Level 4

Excel file of puzzles and previous week’s factor solutions: 12 Factors 2014-07-28

2014-30 Level 4 Logic

183 and Level 4

183 is a composite number.
Factor pairs: 183 = 1 x 183 or 3 x 61
Factors of 183: 1, 3, 61, 183
Prime factorization: 183 = 3 x 61

Notice this for 183: 1 + 8 + 3 = 12 which is a multiple of 3, so 183 is also a multiple of 3.


2014-29 Level 4

Excel file of puzzles and previous week’s factor solutions: 10 Factors 2014-07-21

2014-29 Level 4 Logic

177 and Level 4

177 is a composite number.
Factor pairs: 177 = 1 x 177, 3 x 59
Factors of 177: 1, 3, 59, 177
Prime factorization: 177 = 3 x 59

Here is a magic square made entirely of prime numbers:

prime magic square

What number do you get when you add up the numbers of any one of its rows, columns, or diagonals?

According to Wikipedia, you can’t get a smaller magic sum than 177 when all the numbers in the magic square are prime numbers. Wolfram MathWorld has several Prime Magic Squares of various dimensions up to 13 × 13. Two of the squares include the number 1, which is not a prime number but is sometimes permitted to be in a prime magic square because it is not a composite number.

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2014-28 Level 4

Excel file of puzzles and previous week’s factor solutions: 12 Factors 2014-07-14

2014-28 Level 4 Logic

164 and Level 4

164 is a composite number.
Factor pairs: 164 = 1 x 164, 2 x 82, or 4 x 41
Factors of 164: 1, 2, 4, 41, 82, 164
Prime factorization: 164 = 2 x 2 x 41, which can be written 164 = (2^2) x 4

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2014-26 Level 4

Excel file of puzzles and previous week’s factor solutions: 12 Factors 2014-06-30

2014-26 Level 4 Logic

158 and Level 4

158 is a composite number.
Factor pairs: 158 = 1 x 158 or 2 x 79
Factors of 158: 1, 2, 79, 158
Prime factorization: 158 = 2 x 79

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2014-25 Level 4

Excel file of puzzles and previous week’s factor solutions: 10 Factors 2014-06-23

2014-25 Level 4 Logic

152 and Level 4

152 is a composite number.
Factor pairs: 152 = 1 x 152, 2 x 76, 4 x 38, or 8 x 19
Factors of 152: 1, 2, 4, 8, 19, 38, 76, 152
Prime factorization: 152 = 2 x 2 x 2 x 19, which can be written (2^3) x 19

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2014-24 Level 4

Excel file of puzzles and previous week’s factor solutions: 12 Factors 2014-06-16

2014-24 Level 4 Logic

145 and Level 4

145 is a composite number. Factor pairs: 145 = 1 x 145, 5 x 29. Factors of 145: 1, 5, 29, 145. Prime factorization: 145 = 5 x 29.

 

2014-23 Level 4

Excel file of puzzles and previous week’s factor solutions: 10 Factors 2014-06-09

2014-23 Level 4 Logic

137 and Level 4

  • 137 is a prime number.
  • Prime factorization: 137 is prime.
  • The exponent of prime number 137 is 1. Adding 1 to that exponent we get (1 + 1) = 2. Therefore 137 has exactly 2 factors.
  • Factors of 137: 1, 137
  • Factor pairs: 137 = 1 x 137
  • 137 has no square factors that allow its square root to be simplified. √137 ≈ 11.7046999

How do we know that 137 is a prime number? If 137 were not a prime number, then it would be divisible by at least one prime number less than or equal to √137 ≈ 11.7. Since 137 cannot be divided evenly by 2, 3, 5, 7, or 11, we know that 137 is a prime number.

137 is never a clue in the FIND THE FACTORS puzzles.

2014-22 Level 4

Excel file with puzzles and the previous week’s factor solutions: 12 Factors 2014-06-02

2014-22 Level 4 Logic

131 and Level 4

  • 131 is a prime number.
  • Prime factorization: 131 is prime.
  • The exponent of prime number 131 is 1. Adding 1 to that exponent we get (1 + 1) = 2. Therefore 131 has exactly 2 factors.
  • Factors of 131: 1, 131
  • Factor pairs: 131 = 1 x 131
  • 131 has no square factors that allow its square root to be simplified. √131 ≈ 11.4455

How do we know that 131 is a prime number? If 131 were not a prime number, then it would be divisible by at least one prime number less than or equal to √131 ≈ 11.4. Since 131 cannot be divided evenly by 2, 3, 5, 7, or 11, we know that 131 is a prime number.

131 is never a clue in the FIND THE FACTORS puzzles.

2014-21 Level 4

Excel file of puzzles and previous week’s solutions: 10 Factors 2014-05-26

2014-21 Level 4 Logic