For example, say I have $500 and I need to take 10% of it. Then later I need to take 5% of the next number:
500 - (500 * .10) = 450
450 - (450 * .5) = 427.5
What's the simplest formula for taking continual percentages of the next number (this may continue x number of times).
So, for example:
3% of 4% of 2% of 8% of $1,000.
The way above is too slow for calculations on hundreds of thousands of rows in a database when added to the other queries we're making, so we're looking for a faster route.
When you say "take $10\%$ of it" you really mean "multiply it by $90\%$" Then $500 \cdot 0.90 \cdot 0.95=427.5$, so when you say $3\%$ of $4\%$ of $2\%$ of$ 8\%$ of $\$1,000$ it is really $0.97 \cdot 0.96 \cdot 0.98 \cdot 0.92 \cdot \$1000\approx \$839.57$
Note that when most people say $3\%$ of $1000$ they mean $30$, not $970$