A Multiplication Based Logic Puzzle

157 and Level 3

157 is a prime number. Factor pairs: 157 = 1 x 157. Its only factors are 1 and 157. Prime factorization: none

How do we know that 157 is a prime number? The square root of 157 is an irrational number approximately equal to 12.53. If 157 were not a prime number, then it would be divisible by at least one prime number less than or equal to 12.53. Since 157 cannot be divided evenly by 2, 3, 5, 7, or 11, we know that 157 is a prime number.

2014-25 Level 3

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

A Logical Approach to FIND THE FACTORS: Find the column or row with two clues and find their common factor. Write the corresponding factors in the factor column (1st column) and factor row (top row).  Because this is a level three puzzle, you have now written a factor at the top of the factor column. Continue to work from the top of the factor column to the bottom, finding factors and filling in the factor column and the factor row one cell at a time as you go.

2014-25 Level 3 Factors


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