How many integers between 1 and 10^20 are such that the sum of their digits is 2?	Choose the correct choice: A) 190 B) 210 C) 211 D) 230 E) 231
The integers with a sum of 2 are:   2, 20, 200,...,2*10^19 and there are 20 integers in this list.   Also, these integers have a sum of 2:   11   101, 110   1001, 1010, 1100   etc...   The number of integers in this list is 1 + 2 + ... + 19   Thus, the total number of integers is 1 + 2 + ... + 19 + 20 = 20*21/2= 
<gadget id="calculator">20*21/2</gadget>
<output>210</output>
210   The answer is 210.
<result>B</result>
How many integers between 1 and 10^20 are such that the sum of their digits is 2?