Mental Math · Multiplication Tricks
Big multiplications look slow, but each one hides a friendly cut that makes it easy. Try each problem first, then watch the trick fire.
1 Explore — try these first
Try before you watch. Pick a level below and give the problem an honest try on paper first — wrong turns and all. Then open the video to see the trick. Every level rides one habit: Bend a factor into a friendlier shape, do the easy multiply, then pay it back — one rectangle, many cuts, one answer.
★ · Factor Pairs
These look like hard multiplications: 16 × 25, 18 × 50, and 24 × 25. Try 16 × 25 in your head first.
L0 · Double and Halve
Each of these feels awkward in your head: 35 × 6, 25 × 8, and 45 × 4. Try 35 × 6 first.
L1 · Times-Five is Times-Ten Halved
Three quick fives in your head: 26 × 5, 48 × 5, and 84 × 5. Start with 48 × 5.
L2 · Distribute (Break-Apart)
These are easy to write but hard to see at a glance: 6 × 34, 7 × 23, and 8 × 45. Try 7 × 23 in your head.
L3 · Greatest Product Under a Cap
From the cards 6, 12, 16, and 18, pick two different cards — one for the rows, one for the columns of a tray. Rows × columns is the number of kits, but the tray holds at most 200 kits. Which two cards make the fullest tray without going over?
L4 · Times-Eleven by Adding Neighbours (with carry)
Each of these looks like real multiplication work: 11 × 36, 11 × 54, and 11 × 76. Try 11 × 36 first.
L5 · Squaring Near a Base
Some squares look hard: 25², 35², and 48². Try 35² first.
2 Learn — watch the solutions
Gave each one a real try? Now watch the trick. (Stuck is fine — that's the point.)
★ · Factor Pairs
Peek the trick — Factor Pairs
If a factor sits next to a friendly hundred-maker like 25 or 50, regroup the factors so one pair makes a round 100, then multiply.
L0 · Double and Halve
Peek the trick — Double and Halve
If one factor is even, halve it and double the other — the rectangle keeps the same area, but the multiply gets easier.
L1 · Times-Five = Ten Then Halve
Peek the trick — Times-Five = Ten Then Halve
Five is just half of ten, so to multiply by 5, multiply by 10 (add a zero) and then halve.
L2 · Break Apart (Distribute)
Peek the trick — Break Apart
If a factor is awkward, cut it into tens and ones, multiply each slice, then add the slices back together.
L3 · Greatest Product Under a Cap
Peek the trick — Greatest Product Under a Cap
To pick two different numbers whose product is as big as possible but still at most a limit, start with the two largest; if they go over, step the larger one down to the next value until it fits.
L4 · Eleven Adds Neighbours
Peek the trick — Eleven Adds Neighbours
To multiply a 2-digit number by 11, keep the outer digits and drop their sum in the middle — and carry 1 to the left when that middle sum is 10 or more.
L5 · Square Near a Base
Peek the trick — Square Near a Base
If the number ends in 5, write n × (n + 1) and tack on 25; if it sits near a round base, square the base and trim or add the strips.
3 Master — practice on your own
Print the practice sheet and solve without the videos. Check your answers at the back — if one is wrong, the answer key names the trick so you know exactly which video to rewatch.
Download fresh practice problems PDF
