Estimate a Sum
456 + 267
Round to the nearest 10 and solve
460 + 270 = 730
478 + 135 = ?
Use column addition, partial sums, or any other method to solve
613
821 - 673 = ?
Use Expand and Trade, or any other method to solve.
148
4x4
Create an array and solve
16
I had a fridge with 5 shelves. There were 9 sandwiches on each shelf. A refrigerator repairman added another shelf, so I added 9 more sandwiches.
Solve the helper fact, then add a group to solve the second part of the problem.
9x5=45
9x6 = 54
318 - 198 = ?
Round to the nearest 100 to estimate.
300-200=100
6x6
36
There were 10 rows of trees with 9 trees in each row.
One row of trees were cut down. Now how many trees are left?
Use the helper fact to solve the second part of the problem.
10x9=90
9x9=81
9x9