The [MU] key is used for markup. Here is an example of the markup function. If the purchase price of an item is $120 and the profit rate is 25%, what would the selling price and profit be?
Enter the following:
120 [MU] 25 [%] (result 160)
[=] (result 40)
The selling price would be $160 and the profit would be $40.
To clarify further, the profit rate is relative to the selling price, meaning the percentage of the selling price that is profit. In the example above, the selling price (as computed by the calculator) is $160, so the profit rate of 25% gives a profit of $40.
Before performing the calculation, we did not know what the selling price would be, just that the purchase price of $120 should be 75% of that unknown amount (as 100% - 25% = 75%). To look at it another way, we are asking the calculator to tell us the number that $120 is 75% of. $160 is that number, and then 25% of that (the profit) is $40.