What is sum of the numbers 1 through 1000000?

Answer 1

Oh, dude, you want me to add up all the numbers from 1 to a million? Like, seriously? That's gonna take forever. But hey, if you really wanna know, the sum of all those numbers is 500,000,500,000. Yeah, that's a lot of zeros.

Answer 2

Method 1 (Sum of the first n numbers): The sum of the first n positive integers is n(1 + n)/2 So the sum would be 1,000,000 * (1,000,001)/2 = 500,000,500,000. Method 2 (Algebraic Solution): Let x be the sum of the numbers 1 through 1,000,000. x = 1 + 2 + ... + 999,999 + 1,000,000. x = 1,000,000 + 999,999 + ... + 2 + 1 Adding these equations gives: 2x = 1,000,001 + 1,000,001 + ... + 1,000,001 + 1,000,001 Note that there are 1,000,000 different 1,000,001's in the above equation. So: 2x = 1,000,001(1,000,000) = 1,000,001,000,000 x = 500,000,500,000.