Question

Use the Identity (x + a)(x + b) = x² + (a + b)x + ab to find the following:

501 × 502

Answer 1

501 × 502
= (500 + 1) × (500 + 2)
= 500² + (1 + 2) × 500 + 1 × 2
= 250000 + 1500 + 2
= 251502.