Add 2-digit numbers in your head
Add the tens first, then the ones. No carrying on paper.
How long?
Type the answer. Correct answers move on by themselves. Press Enter to skip a wrong one.
How the trick works
- Keep the first number whole.
- Add the tens of the second number.
- Then add the ones.
Worked examples
47 + 38: add the tens first, 47 + 30 = 77.
Then the ones: 77 + 8 = 85.
65 + 27: add the tens first, 65 + 20 = 85.
Then the ones: 85 + 7 = 92.
38 + 46: add the tens first, 38 + 40 = 78.
Then the ones: 78 + 6 = 84.
Practise it
Take the 1 minute drill above a few times. When you can do most of them without slowing down, try level 2, which mixes this trick with others.