nth term of the series containing one 9 then two 9 and so on

Question

nth term of the series 9, 99, 999, 9999.

Is there any formula for it?

9

99

999

9999

. . . .

9...9 with n 9’s equals 10^n - 1. – Jonas De Schouwer Mar 08 '19 at 19:11 — Jonas De Schouwer, Mar 08 '19 at 19:11

score 4 · Accepted Answer · answered Mar 08 '19 at 19:11

4

The general formula is $$10^n-1$$ as each term is one less than a power of $10$.

answered Mar 08 '19 at 19:11

Peter Foreman

1 Answers1