A Multiplication Based Logic Puzzle

643 and Level 1

Here’s an interesting prime factorization: (2^6)⋅3⋅643 = 123456. Did you notice its largest prime factor? Thank you Stetson.edu for that fun fact about the number 643.

643 Puzzle

Print the puzzles or type the solution on this excel file: 10 Factors 2015-10-12

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  • 643 is a prime number. 641 and 643 are twin primes.
  • Prime factorization: 643 is prime and cannot be factored.
  • The exponent of prime number 643 is 1. Adding 1 to that exponent we get (1 + 1) = 2. Therefore 643 has exactly 2 factors.
  • Factors of 643: 1, 643
  • Factor pairs: 643 = 1 x 643
  • 643 has no square factors that allow its square root to be simplified. √643 ≈ 25.357444666.

How do we know that 643 is a prime number? If 643 were not a prime number, then it would be divisible by at least one prime number less than or equal to √643 ≈ 25.4. Since 643 cannot be divided evenly by 2, 3, 5, 7, 11, 13, 17, 19, or 23, we know that 643 is a prime number.

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643 Factors

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