I usually choose the largest portion to take up the slack. so multiply each
of the percentages by the original except one and make that value equal to
the original minus the sum of the other results

50 * 21% = x
50 * 29% = y
50 * 19% = z
w = 50 - sum(x, y, z) <== approximates 31%

--
Regards,
Tom Ogilvy


"Stephen" wrote:

I am trying to mulitply an original number (say 50) by a series of
percentages adding up to 100%. When Excel adds them together, due to
rounding, they don't add up to the original number. Do you know how I can
get it to round correctly to get the original number?