Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 738 · 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. 1.982 − 629 =
2. 2.904 − 697 =
3. 3.462 − 299 =
4. 4.854 − 439 =
5. 5.821 − 799 =
6. 6.647 − 559 =
7. 7.397 − 199 =
8. 8.951 − 507 =
9. 9.956 − 667 =
10. 10.425 − 197 =
11. 11.573 − 178 =
12. 12.612 − 539 =
13. 13.574 − 429 =
14. 14.652 − 598 =
15. 15.428 − 237 =
16. 16.743 − 649 =
17. 17.500 − 458 =
18. 18.505 − 298 =
19. 19.850 − 798 =
20. 20.512 − 397 =
21. 21.841 − 637 =
22. 22.554 − 499 =
23. 23.851 − 298 =
24. 24.800 − 319 =
25. 25.432 − 279 =
26. 26.965 − 797 =
27. 27.812 − 199 =
28. 28.390 − 118 =
29. 29.829 − 297 =
30. 30.480 − 299 =
31. 31.610 − 538 =
32. 32.902 − 698 =
33. 33.865 − 439 =
34. 34.965 − 638 =
35. 35.847 − 449 =
36. 36.894 − 208 =
37. 37.918 − 199 =
38. 38.958 − 699 =
39. 39.644 − 308 =
40. 40.844 − 608 =

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