The average of 9 consecutive numbers is 20. The smallest of these numbers is :

10 20 16 12

16

Let the smallest number of the series be x x + (x + 1) + .....+ (x + 7) + (x + 8) = 20 x 9 ⇒ 9x + ( 1 + 2 + ....+ 7 + 8) = 180 ⇒ 9x + 36 = 180 ⇒ x = \(\frac{180 - 36}{9}\) ⇒ x = 16 ∴ The smallest of these numbers is 16