Question

The product of three consecutive numbers is 990. What is the sum you f the 3 whole numbers?

Answer 1

20

Explanation:

If the three numbers are x, x+1, and x+2, then:

x (x+1) (x+2) = 990

x (x² + 3x + 2) = 990

x³ + 3x² + 2x - 990 = 0

(x - 9) (x² + 12x + 110) = 0

Since x must be a whole number, x = 9. You can also use simple trial and error to find that the three numbers are 9, 10, 11.

The sum is:

9 + 10 + 11 = 20