Let’s apply the 7 divisibility trick to **40**6.

- Separate the last digit from the rest and multiply that last digit by two: 6 x 2 = 12.
- Now find the difference between the remaining number,
**40**and 12:**40**– 12 = 28. - Since 28 is a multiple of 7, we know that 406 is also divisible by 7.

Print the puzzles or type the factors on this excel file: 12 Factors 2015-02-23

- 406 is a composite number.
- Prime factorization: 406 = 2 x 7 x 29
- 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 x 2 x 2 = 8. Therefore 406 has exactly 8 factors.
- Factors of 406: 1, 2, 7, 14, 29, 58, 203, 406
- Factor pairs: 406 = 1 x 406, 2 x 203, 7 x 58, or 14 x 29
- 406 has no square factors that allow its square root to be simplified. √406 ≈ 20.1494