Multiply by 9
Multiply by 10, then subtract the original.
48 × 9 = 432
Nine 48s is ten 48s with one taken back: 480 − 48.
Take the 48 in two bites: 480 − 40 = 440, then 440 − 8 = 432.
Your turn
Three to try in your head — tap what you get.
99 × 9
79 × 9
80 × 9
All 36 shortcuts: the Magic Tricks library.