Magic teaches math in this fun presentation:
Ask your volunteer/student to pick a number between 1-100, but don’t tell what it is!
(If kids are younger, have them pick between 1-9 to make it easier; if you’re doing this with adults, have them pick a SUPER big number to make it more fun!)
They’ll be astounded when you PREDICT their NUMBER so quickly!
First, have them multiply their number by 2, then multipy that number by 5.
When they tell you the resulting figure on their calculator (or in their heads), you ask them to DROP the ZERO from that figure, and then announce the FINAL number: it matches EXACTLY the number they had secretly picked!
5683 X 2 = 11,366 X 5 = 56,830 (drop the last 0) = 5683
Try it with HUGE numbers, it still works!