yogi_Compute Running Total Of Entries Successively Multiplied By A Constant

Yogi Anand, D.Eng, P.E.                                         Google Spreadsheet                            www.energyefficientbuild.com

andie856603 asked:
what formula do i use to keep a running total of X when this number decreases by .75
o.k i'll try to explain as best i can this is for a game i'm playing
number 1 for example is worth 2601, #2 is .75 of #1(1951), #3 is 0.75 of #2 (1463) and so on
what formula would i use so when i change #1 it will add it
i basically want to do X + .75of X+ .75 of Y + .75 of Z and so on
hope you understand this
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In the following solution, the starting entry is housed in cell A1, and the multiplying factor is housed in cell B1 ... so here we go