Explain why 7 x 13 x 11 + 11 and (7 x 6 x 5 x 4 x 3 x 2 x 1) + 3 are composite numbers.
Answer»
Solution: 7 x 13 x 11 + 11 = (7 x 13 + 1) x 11 = (91 + 1) x 11 = 92 x 11 = (2 x 2 x 23) x 11 = 2 x 2 x 11 x 23 Since 7 x 13 x 11 + 11 can be expressed as a product of primes, it is a composite number. (7 x 6 x 5 x 4 x 3 x 2 x 1) + 3 = (7 x 6 x 5 x 4 x 2 x 1 + 1) x 3 = (1680 + 1) x 3 = 1681 x 3 = (41 x 41) x 3 = 3 x 41 x 41 Since (7 x 6 x 5 x 4 x 3 x 2 x 1) + 3 can be expressed as a product of primes, it is a composite number.