Calculating S&P 500 return per month in percentages?

Question

How do you do so? I'll throw out some numbers for you guys.
November 1- 1361.81
November 30- 1400.63

so what was the percentage gain for the month?

Answer 1

subtract 1361.81 from 1400.63 then divide that by 1361.81 ........soooooo its 1400.63-1361.81 = 38.82/1361.81 = .0285 which equals a 2.9% increase for november

Answer 2

That is just the increase for the month. You can make the calculation simpler by dividing the ending balance by the beginning balance to get the same answer.

To calculate the actual return you will need to know your basis to see the gain.