Mental Math
What is 45 + 10 = ?
55
Round 67 to the nearest 10.
70
Solve: 125 + 342.
467
Solve: 87 - 35
52
Sarah has 24 stickers and her brother gives her 15 more. How many stickers does she have now?
39
Solve this using the "friendly numbers" strategy: 39 + 52
39 becomes 40. 40 + 52 = 92, then subtract 1, = 91
Estimate the sum of 42 + 39 by rounding to the nearest 10.
82 (81)
Use the "breaking apart using place value" strategy to solve 56 + 27.
(50 + 20) + (6 + 7) = 70 + 13 = 83
Solve 452 - 131
321
There were 92 apples in a crate. 45 were sold. How many apples are left?
47
What is 150 - 60 = ?
90
Is the answer to 88 - 31 closer to 50 or 60?
60
Solve 458 + 261. Don't forget to regroup the tens!
719
Solve 500 - 275
225
The Grade 3 class raised $145 for a field trip on Monday and $210 on Tuesday. What is the total amount raised?
355
Starting at 245, count backward by 10s three times. What is your final number?
215
You have $5.00. You want to buy a toy for $2.15 and a snack for $1.90. Estimate to see if you have enough money.
Yes, 2 + 1 = 3.
Find the missing number: 350 + ___ = 500.
150
Solve 624 - 358
266
A library has 800 books. 230 are checked out on Monday and 115 are checked out on Tuesday. How many books are still in the library?
455
Solve 950 - 499 in your head. Explain the strategy you used.
451
Use rounding to estimate the answer to 432 + 278 + 112. Round each to the nearest hundred.
800 (400 + 300 + 100).
Find the missing digits for the letters A and B: 4A7 + 23B = 682.
A = 4, B = 5. (447 + 235 = 682).
Solve 789 - 345
444
A bakery made 500 cookies. They sold 185 in the morning and 215 in the afternoon. How many cookies were not sold?
100