Question

Find the product by using the formula.

(8) 203 × 197

Answer 1

203 × 197
203 = 200 + 3
197 = 200 − 3
∴ 203 × 197 = (200 + 3) (200 − 3)
The expression (200 + 3) (200 − 3) is of the form (a + b) (a − b).
Thus, we can use the identity (a + b) (a − b) = a² − b² .
∴ 203 × 197 = (200 + 3) (200 − 3)
= (200)² − (3)²
= 40000 − 9
= 39991