Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 913 · 40 questions

How to do it in your head (Round up, add back): Round the number you take away up to the next ten or hundred: 297 → 300 (3 too many). Take away the round number. Add back the extra, because you took away too much.

1. 1.778 − 697 =
2. 2.982 − 297 =
3. 3.950 − 798 =
4. 4.823 − 798 =
5. 5.542 − 247 =
6. 6.628 − 548 =
7. 7.878 − 497 =
8. 8.761 − 399 =
9. 9.699 − 387 =
10. 10.702 − 469 =
11. 11.588 − 467 =
12. 12.745 − 327 =
13. 13.909 − 799 =
14. 14.720 − 488 =
15. 15.694 − 297 =
16. 16.981 − 197 =
17. 17.730 − 669 =
18. 18.640 − 398 =
19. 19.954 − 697 =
20. 20.884 − 149 =
21. 21.927 − 489 =
22. 22.654 − 298 =
23. 23.232 − 129 =
24. 24.936 − 227 =
25. 25.698 − 188 =
26. 26.615 − 199 =
27. 27.738 − 657 =
28. 28.994 − 199 =
29. 29.853 − 549 =
30. 30.565 − 397 =
31. 31.958 − 597 =
32. 32.741 − 507 =
33. 33.634 − 599 =
34. 34.931 − 498 =
35. 35.968 − 248 =
36. 36.798 − 687 =
37. 37.511 − 477 =
38. 38.822 − 497 =
39. 39.540 − 159 =
40. 40.456 − 298 =

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