2-min Fluency Warm-up — Mental math: add or subtract 10.
43 + 10 =
76 − 10 =
52 + 10 =
89 − 10 =
If the ones aren't enough, borrow from the tens. Cross out the ten and write the new number above.
Remember: crossing out the ten means it becomes one less!
Estimate First! Round to tens, estimate the difference, then calculate.
53 − 17
Round: 50 − 20 = 30
Estimate:
Actual:
72 − 28
Round: 70 − 30 = 40
Estimate:
Actual:
61 − 24
Round: 60 − 20 = 40
Estimate:
Actual:
85 − 37
Round: 90 − 40 = 50
Estimate:
Actual:
Find the missing number. Think: what goes in the blank?
60 − = 25
− 42 = 32
83 − = 56
− 31 = 52
Write each step. Show where you borrow.
53 − 17
Ones: 3 − 7? Can't do it!
Borrow: 53 = 4 tens + 13 ones
Ones: 13 − 7 =
Tens: 4 − 1 =
Answer:
72 − 28
Ones: 2 − 8? Can't do it!
Borrow: 72 = 6 tens + 12 ones
Ones: 12 − 8 =
Tens: 6 − 2 =
Answer: