Normally, the function returns x divided by 100. However, it does perform a more useful function when the previous operation was addition or subtraction, then the number returned is the specified percentage of y. For example,

Pressing displays the number 0.15.

Pressing displays the number 15 (since 30% of 50 is 15). The result after pressing is 65.

In RPN mode, the result is always the specified percentage of y. The value of y is preserved so that subsequent operations can be performed without having to re-enter the base number.