Add and subtract

Add and subtract using the most efficient strategies.

WALT - solve addition and subtract problem using the most efficient strategies.

SUCCESS CRITERIA - To be successful I need to remember ‘RUCSAC’ when solving word problems.

1. In Glen Innes school there are 84 boys and 89 girls. Find the number of students at Glen Innes School.

89 + 84 = 173

• 89 + 1 = 90
• 84 - 1 = 83
• 90 + 83 = 173

Rounding and Compensating. 👍

2. A shopkeeper bought 245 eggs and sold 78 eggs. How many eggs were left unsold?

245 - 78 = 167

• 245 - 5 = 240
• 240 - 78 = 162
• 162 + 5 = 167

Rounding and Compensating 👍

3. Dora got $325 from her father and $89 from her mother. How much money does she have now?

325 + 89= 414

• 325 + 5 = 330
• 89 + 330 = 419
• 419 - 5 = 414

Rounding and Compensating👍

4. Gary played a car game and scored 453 points in first round and 173 points in second round. The game was over after the second round. How many points did he have at the end of the game?

453 + 173 = 626

• 453 + 7 = 460
• 173 + 460 = 633
• 633 - 7 = 626

Rounding and Compensating. 👍

5. An animal care society tested 356 pet animals. 229 were infected by diseases. Find the number of healthy pet animals that participated in the medical tests.

356 - 229=127

• 356 - 6 = 350
• 229 - 350 = 121
• 121 + 6 = 127

Rounding and Compensating👍

6. In an annual celebration, 674 students participated. Of them, 397 were boys. Find the number of girls who participated.

674 - 397 =277

• 674 - 4 = 670
• 670 - 397 = 273
• 273 + 4 = 277

Rounding and Compensating👍

7. There are 2236 lions and 5987 tigers in a forest. These are the only wild animals in the forest. Find the total number of wild animals in the forest.  

2236 + 5987 = 8223

• 2236 + 4 = 2240
• 2240 + 5987 = 8227
• 8227 - 4 = 8223

Rounding and Compensating👍

8.Mark has a book which contains 6644 pages. He has already read 2979 pages. How many pages are unread?

6644 - 2979 = 3665

• 6644 + 6 = 6650
• 6650 - 2979 - 3671
• 3671 - 6 = 3665

Rounding and Compensating👍

9.In a public telephone booth, 243 calls are made before noon and 389 calls are made after noon. Find the number of calls made in a day.

243 + 389 = 632

• 243 - 3 = 240
• 389 + 240 = 629
• 629 + 3 = 632

Rounding and Compensating👍

10.Director James directed a film which ran for 248 minutes. During the editing process, 109 minutes were removed. What is the final running time of the film, after editing?

248 - 109 =  139

• 248 + 2 = 250
• 250 - 109 = 141
• 141 - 2 - 139

Rounding and Compensating 👍