Question

Write the smallest 4-digit number and express it as a product of primes.

Answer 1

The smallest 4-digit number is 1000.

1000 = 2 × 500
= 2 × 2 × 250
= 2 × 2 × 2 × 125
= 2 × 2 × 2 × 5 × 25
= 2 × 2 × 2 × 5 × 5 × 5

∴ 1000 = 2 $\times$2 $\times$ 2 $\times$ 5 $\times$ 5 $\times$ 5