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I'm trying to work out a short formula for calculating the final amount if paying in $1000 per month with an annual ROI of 45%...

Spreadsheet

At the moment, I am having to enter the ROI% in 12 times

(45*12+45*11+45*10+45*9+45*8+45*7+45*6+45*5+45*4+45*3+45*2+45*1)/(12*100)

but there must be a shorter way I've forgotten from my school days

Christian
  • 91

1 Answers1

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Got it! Sum of series :)

S = ROI * n(a1+an)/2

=45 * 12(1+12)/2

Christian
  • 91