Math practice · Week 7 · Wednesday
I can use a friendly number to add or subtract.
Look: 59 + 34
- 59 is close to 60. Borrow 1 to make 60.
- Add: 60 + 34 = 94.
- Give back the 1: 94 − 1 = 93. So 59 + 34 = 93.
Circle the number close to a ten. Write the friendly problem first. Then solve.
- 69 + 24 = ____Answer: 93 (70 + 24 = 94, 94 − 1 = 93)
- 29 + 58 = ____Answer: 87 (30 + 58 = 88, 88 − 1 = 87)
- 48 + 37 = ____Answer: 85 (50 + 37 = 87, 87 − 2 = 85)
Now subtract. Take away the friendly number, then add back.
- 73 − 29 = ____Answer: 44 (73 − 30 = 43, 43 + 1 = 44)
- 86 − 39 = ____Answer: 47 (86 − 40 = 46, 46 + 1 = 47)
- 64 − 18 = ____Answer: 46 (64 − 20 = 44, 44 + 2 = 46)
Challenge
- Name three friendly numbers.Answer: Answers vary. Any three tens, such as 20, 50 and 90.
Second Grade · Week 7 · Wednesday · secondgrade.com