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What do all the two-digit numbers (10 to 99) add up to?

Class 10Sum of n Terms of an APAlgebra — Sequences

A4905
B5395
C4415
D9810

Step-by-Step Solution

Two-digit numbers: 10,11,...,99.

n = 90, a = 10, l = 99. S = \frac{90}{2}

(10 + 99) = 45 (109) = 4905

.

Answer: A) 4905

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