Q14 REPRESENTATIONS

Suppose n is an integer such that the sum of digits on n is 2, and 10^10<n <10^11. The number of different values of n is

a. 11

b. 10

c. 9

D. 8

The answer is B.

10,000,000,000 < n < 100,000,000,000
—> 10,000,000,001
—> 10,000,000,010
—> 10,000,000,100
—> 10,000,001,000
—> 10,000,010,000
—> 10,000,100,000
—> 10,001,000,000
—> 10,010,000,000
—> 10,100,000,000
—> 11,000,000,000 

Also, we got 20,000,000,000

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