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Try this **=((C1*(C1+1))/2)*A1*(1+B1/12)**

where A1 = Monthly Amount, B1 = Annual Interest Rate and C1 = Number of Months

Put formula in D1 to give result

Originally posted by **RacingDriver**
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Thank you very much! I think that does it. The way I tried using a row for every month was close, but there is a flaw. It came out 5.2 mil (over 240 months) instead of 5.7mil. I feel like it is in the way I have it compounding (monthly vs annual, or something) Here is the (simple) formula that I used. I just did 1 row for 240 months, 1 for 239 months, one row for 238, etc. If you have a moment, since you seem to really understand this stuff, could you reply, with what I did to have it come out different?

A B C D E F

1 8% 240 -100 $58,902.04

2 8% 239 -100 $58,412.62

3 8% 238 -100 $57,926.45

A Row number only

B interest rate

C number of months the $100 is invested

D amount invested ($100)

E I didnt enter any value for E

Formula =FV(B8/12,C8,D8,E8)

I still look at your formula, and have a tough time "getting it". But, I sure do appreciate the ones, like you, who do. I have a question for you too - how long did it take you to figure that out? Just curious