Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 218 · 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. 1.624 − 599 =
2. 2.471 − 118 =
3. 3.585 − 569 =
4. 4.481 − 298 =
5. 5.733 − 697 =
6. 6.546 − 409 =
7. 7.576 − 519 =
8. 8.429 − 377 =
9. 9.966 − 799 =
10. 10.780 − 298 =
11. 11.481 − 398 =
12. 12.798 − 169 =
13. 13.889 − 799 =
14. 14.939 − 317 =
15. 15.739 − 299 =
16. 16.946 − 799 =
17. 17.739 − 499 =
18. 18.489 − 119 =
19. 19.203 − 128 =
20. 20.702 − 418 =
21. 21.515 − 399 =
22. 22.542 − 139 =
23. 23.663 − 199 =
24. 24.799 − 198 =
25. 25.704 − 549 =
26. 26.585 − 288 =
27. 27.644 − 599 =
28. 28.547 − 399 =
29. 29.366 − 197 =
30. 30.964 − 699 =
31. 31.943 − 558 =
32. 32.860 − 649 =
33. 33.784 − 429 =
34. 34.977 − 297 =
35. 35.449 − 147 =
36. 36.665 − 599 =
37. 37.811 − 567 =
38. 38.534 − 278 =
39. 39.273 − 228 =
40. 40.931 − 697 =

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