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Well, 10^2-16=84 and 10^3-16 = 984. So, we see the exponent tells us the number of digits involved in our answer (2 in the former case, 3 in the latter).

10^2^0-16=999...984; two numbers are the 8 and the 4, whereas the other eighteen are 9s!

Yes D is correct answer. If you subtract 1 from 10^20 it will be 999(20 times) if you subtract 15 more from that, you will get last digit 4 second last 8 and all others 9. So answer is D.

Yes D is correct answer. If you subtract 1 from 10^20 it will be 999(20 times) if you subtract 15 more from that, you will get last digit 4 second last 8 and all others 9. So answer is D.

I did it the same way. Subtracting 1 first seemed to help me visualize it.

10^2^0 would be a 21 digit number ... subtract 16 and you are left with a 20 digit number with 2 digits as 4 and 8 and the rest 9s. The total is 8+4+18*9 = 174 therefore (D) _________________

What is the sum of the digits in decimal notation of number 10^{20}-16?

A. 158 B. 162 C. 165 D. 174 E. 183

10^{20} has 21 digits: 1 followed by 20 zeros; 10^{20}-16 has 20 digits: 18 9's and 84 in the end;

So, the sum of the digits of 10^{20}-16 equals to 18*9+8+4=174.

Answer: D.

D can't be the answer. once we subtract 16 from 10^20 we have only 19 numbers left. among 19 numbers 17 are nine and last two are 8 and 4. therefor sum is 17*9+8+4=165

What is the sum of the digits in decimal notation of number 10^{20}-16?

A. 158 B. 162 C. 165 D. 174 E. 183

10^{20} has 21 digits: 1 followed by 20 zeros; 10^{20}-16 has 20 digits: 18 9's and 84 in the end;

So, the sum of the digits of 10^{20}-16 equals to 18*9+8+4=174.

Answer: D.

D can't be the answer. once we subtract 16 from 10^20 we have only 19 numbers left. among 19 numbers 17 are nine and last two are 8 and 4. therefor sum is 17*9+8+4=165

Nope.

10^{20} has 21 digits: 1 followed by 20 zeros: 100,000,000,000,000,000,000

10^{20}-16 has 20 digits: 18 9's and 84 in the end: 99,999,999,999,999,999,984. _________________