Find the sum of all integers 30 to 80. (Is there a formula to do this?

you consider the arithmetic series with first term 30, common difference 1, and last term 80

the sum of arithmetic sequence is n/2 (first term + last term), and there are (80-30) + 1 = 51 numbers so n = 51 and so 51/2 (30+80) = 2805 which represents the sum 30 + 31 + 31 + ... + 78 + 79 + 80

Add all the numbers from 30 to 80 and that is your answer