Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 846 · 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. 1.801 − 699 =
2. 2.958 − 689 =
3. 3.995 − 689 =
4. 4.556 − 399 =
5. 5.415 − 158 =
6. 6.979 − 458 =
7. 7.875 − 219 =
8. 8.657 − 529 =
9. 9.814 − 698 =
10. 10.922 − 799 =
11. 11.503 − 418 =
12. 12.283 − 198 =
13. 13.597 − 468 =
14. 14.868 − 797 =
15. 15.507 − 227 =
16. 16.358 − 198 =
17. 17.830 − 699 =
18. 18.996 − 799 =
19. 19.655 − 589 =
20. 20.842 − 677 =
21. 21.884 − 298 =
22. 22.831 − 529 =
23. 23.943 − 448 =
24. 24.760 − 558 =
25. 25.799 − 538 =
26. 26.671 − 597 =
27. 27.439 − 339 =
28. 28.618 − 499 =
29. 29.198 − 178 =
30. 30.920 − 627 =
31. 31.582 − 359 =
32. 32.661 − 367 =
33. 33.799 − 469 =
34. 34.877 − 797 =
35. 35.522 − 249 =
36. 36.646 − 169 =
37. 37.568 − 499 =
38. 38.619 − 197 =
39. 39.852 − 599 =
40. 40.958 − 297 =

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