Double and Halve
Halve one side, double the other — the product stays the same.
14 × 45 = 630
Halving 14 while doubling 45 just moves a ×2 across. The product never changes.
Now it is easy: 7 × 90 = 630.
Aim the doubling at the number ending in 5 — it becomes a friendly ten.
Your turn
Three to try in your head — tap what you get.
26 × 95
36 × 95
75 × 42
All 36 shortcuts: the Magic Tricks library.