How to Multiply in Your Head: Double Digits, 3 Methods
Here's how to multiply in your head with double digits: split one number into tens and ones, multiply each part, and add the results. So 23 × 14 becomes 23 × 10 = 230 plus 23 × 4 = 92, which is 322. When a number sits just below a round one, round it up and subtract instead, and use two special tricks for numbers near each other and for 11s.
If multi-step arithmetic falls apart because you lose the first part while working on the second, IQ Tester can tell whether that's mental arithmetic or working memory and drill the right one: Find my weak spots.
Split one number
Splitting is the method to learn first, because it works on every pair of two-digit numbers. You break one number into tens and ones and leave the other whole.
Example: 47 × 6 (warm-up with one digit)
- 40 × 6 = 240
- 7 × 6 = 42
- 240 + 42 = 282
Example: 36 × 24
- Split 24 into 20 + 4
- 36 × 20 = 720 (36 × 2 = 72, then add a zero)
- 36 × 4 = 144
- 720 + 144 = 864
Which number should you split?
Split the one that gives easier pieces. For 36 × 24, splitting 24 means multiplying by 20 and 4. Splitting 36 means multiplying by 30 and 6. Both work. Choose the pair of steps you find friendlier.
Work left to right
Always do the big part first. Your running total starts large (720), and you add a smaller piece onto it. That's much easier to hold than working out the ones first and trying to remember them while you do the tens.
Round and adjust
When one number ends in 7, 8 or 9, rounding up is usually faster than splitting.
Example: 29 × 34
- Round 29 up to 30
- 30 × 34 = 1,020
- You used one extra 34, so subtract it: 1,020 − 34 = 986
Example: 48 × 15
- 50 × 15 = 750
- You added two extra 15s (30), so subtract: 750 − 30 = 720
Example: 19 × 23
- 20 × 23 = 460
- 460 − 23 = 437
The rule for adjusting: take off one copy of the other number for every step you rounded up. Rounded 48 to 50? That's two steps, so take off two copies.
This is the same move that powers our guide on how to get better at mental math, and it's worth practising until it's automatic.
Numbers near each other
When two numbers sit an equal distance either side of a round number, there's a beautiful shortcut called the difference of squares trick.
The rule: find the middle number. Square it, then subtract the distance squared.
Example: 48 × 52
- Middle: 50. Distance: 2.
- 50² = 2,500. 2² = 4.
- 2,500 − 4 = 2,496
Example: 61 × 59
- Middle: 60. Distance: 1.
- 3,600 − 1 = 3,599
Example: 37 × 43
- Middle: 40. Distance: 3.
- 1,600 − 9 = 1,591
It only works when the middle is easy to square, so it shines around 20, 30, 40, 50 and 100. For more on squaring, see how to square numbers in your head.
How to multiply numbers close to 100
For two numbers just under 100, count how far each is below 100.
Example: 97 × 94
- 97 is 3 below, 94 is 6 below.
- Take either number minus the other's distance: 97 − 6 = 91 (or 94 − 3 = 91).
- Multiply the distances: 3 × 6 = 18.
- Put them side by side: 9,118
If the distances multiply to a single digit, write it with a leading zero: 98 × 97 → 95 and 06 → 9,506.
The 11s trick
Multiplying a two-digit number by 11 is almost instant.
The rule: write the first digit, then the sum of the two digits, then the last digit.
- 11 × 53: 5, (5 + 3 = 8), 3 → 583
- 11 × 72: 7, (7 + 2 = 9), 2 → 792
If the middle sum is 10 or more, carry the 1 into the first digit.
- 11 × 78: 7, (7 + 8 = 15), 8 → carry the 1 → 858
- 11 × 99: 9, (18), 9 → 1,089
Hold the parts with chunking
Every method above has a moment where you're holding one number while working out another. That's where double digit multiplication usually breaks.
Ways to keep the parts:
- Say the running total out loud or under your breath: "seven-twenty... plus one-forty-four."
- Hold numbers as words, not digit strings. "Seven-twenty" is one chunk. "Seven, two, zero" is three.
- Add small onto big. Keep the larger result in mind and add the smaller piece to it.
- Estimate first. If you know 36 × 24 is "about 35 × 25 = 875," a slip to 764 jumps out.
If you keep losing the first product while working out the second, the problem might not be your times tables at all. It could be working memory, and it's hard to tell the difference by yourself. IQ Tester's 16 questions separate mental arithmetic from working memory, among seven weak spots, and give you a daily drill aimed at whichever you actually have. Find my weak spots
Which method to use
| The numbers look like | Use | Example |
|---|---|---|
| Any two-digit pair | Split one number | 36 × 24 |
| One ends in 7, 8 or 9 | Round and adjust | 29 × 34 |
| Equal distance from a round number | Difference of squares | 48 × 52 |
| Both just under 100 | Distance from 100 | 97 × 94 |
| One number is 11 | The 11s trick | 11 × 78 |
With practice, you'll pick the method in a second, which is the real secret of how to multiply in your head fast.
Practice set
Try each one, choosing your method first. Answers below.
- 17 × 13
- 26 × 15
- 49 × 23
- 61 × 59
- 11 × 64
- 35 × 42
- 96 × 98
- 11 × 87
Answers: 1) 221 (or 15² − 2² = 225 − 4), 2) 390, 3) 1,127 (50 × 23 − 23), 4) 3,599, 5) 704, 6) 1,470, 7) 9,408, 8) 957
Get quicker at double-digit multiplication every day
Now you know how to multiply in your head with double digits: split, round and adjust, use the near-each-other trick, and handle 11s instantly. IQ Tester's 16 questions take about two minutes and show whether mental arithmetic or working memory is your weak spot. Then you get one tip and one short drill a day aimed at it, with a streak and a history to track your progress.
FAQ
What is the easiest way to multiply two-digit numbers in your head?
Split one number into tens and ones, multiply each part by the other number, and add. For 23 × 14, that's 230 + 92 = 322. It works on every pair, so it's the best method to learn first.
How do you multiply double digits in your head fast?
Learn to spot which method fits: round and adjust for numbers ending in 8 or 9, difference of squares for numbers either side of a round number, and the 11s trick. Choosing the right method quickly saves more time than calculating quickly.
What is the trick for multiplying by 11?
For a two-digit number, write the first digit, then the sum of both digits, then the last digit. 11 × 53 is 5, 8, 3, so 583. If the middle sum is 10 or more, carry the 1 to the first digit.
How do you multiply big numbers in your head without losing track?
Work left to right, keep a running total, and add smaller pieces onto it. Say partial answers under your breath and hold them as spoken numbers. Estimating the answer first also helps you catch slips.
Is it worth learning mental multiplication in 2026?
Yes. Phones do the math, but mental multiplication helps you check totals, spot errors and move faster on timed tests. It also builds number sense, which makes estimating in everyday life much easier.