Number Sense & Mental Math
Multiply 23 × 27 in 3 Seconds
Same tens digit + ones that add up to 10? Here's the shortcut:
30 s
Step by step
- Can you do 23 × 27 in 3 seconds?Can you do twenty-three times twenty-seven in three seconds? Here's the trick!
- Same tens digit, ones add up to 10Same tens digit, and the ones digits add up to ten.
- Tens × (next number up): 2 × 3 = 6Tens digit times the next number up: two times three is six.
- Ones × ones: 3 × 7 = 21Ones times ones: three times seven is twenty-one.
- Put them together: 621!Put them together: six hundred twenty-one!
Your turn
Your turn: sixty-four times sixty-six?
Show the answer
Six times seven is forty-two. Four times six is twenty-four. Forty-two twenty-four!
Keep going
There are more short lessons on this topic, each with a full write-up. A free 15-question fractions check-up is coming soon.
