We are given the formula that calculates the sum of consecutive numbers as follows:
[ n(n+1)] / 2
where n is the last number
Now, we want to calculate the sum from 1 to 100. The last number is 100, this means that n=100
Substitute with n=100 in the given equation to get the sum as follows:
sum = [100(100+1)] / 2
sum = [100*101] / 2
sum = 10100 / 2
sum = 5050
Therefore, the correct choice is:
D. 5,050
