Number Sense & Mental Math
Multiply 37 × 77 in 3 Seconds
Same ones digit + tens that add up to 10? Here's the shortcut:
38 s
Step by step
- Can you do 37 × 77 in 3 seconds?Can you do thirty-seven times seventy-seven in three seconds? Here's the trick!
- Same ones digit, tens add up to 10Same ones digit, and the tens digits add up to ten.
- Tens × tens + ones: 3 × 7 + 7 = 28Tens times tens, plus the ones digit: three times seven plus seven is twenty-eight.
- Ones × ones: 7 × 7 = 49Ones times ones: seven times seven is forty-nine.
- Put them together: 2849!Put them together: twenty-eight forty-nine!
Your turn
Your turn: sixty-four times forty-four?
Show the answer
Six times four plus four is twenty-eight. Four times four is sixteen. Twenty-eight sixteen!
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.
