How do you do this problem 1+2+3+4...+100 = ?

Question

What formula do you use to calculate 1+2+3+4...+100 = ?

Answer 1

okay here we go: the first column is the 100 terms listed forward now add the terms backward:

1 + 100 = 101

2 + 99 = 101

3 + 98 =101

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100 + 1 =101

Notice that each individual term ie equal to 101.

so there are 100 occurences and we only need half of it for the answer because we doubled the total.

100/2(101) = 50(101) = 5050