To make this trick work better, you can set it up before hand and add in a parenthese. The parenthese lets you hit multiply right in front of them and not end up with zero after each multiplication. To find the parentheses button on the iphone, turn the calculator sideways. You only have to put the parentheses in at the beginning; the one at the end doesn't matter.
So to set it up this way you are going to do: Your number + 0 x parenthese When you multiply the numbers use the multiplication function, not the equals. When you enter their last number make sure you press equals this time (not multiply). For example the number I want them to end up with is 999,999. So to get this number do: 999,999 + 0 x parenthese ( their birthday x their age x etc... equals =
Hope this helps.