Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 53 · 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. 1.545 − 257 =
2. 2.824 − 508 =
3. 3.906 − 297 =
4. 4.610 − 397 =
5. 5.491 − 278 =
6. 6.917 − 597 =
7. 7.411 − 137 =
8. 8.931 − 467 =
9. 9.701 − 377 =
10. 10.998 − 597 =
11. 11.535 − 519 =
12. 12.657 − 199 =
13. 13.821 − 599 =
14. 14.455 − 299 =
15. 15.626 − 608 =
16. 16.424 − 198 =
17. 17.403 − 258 =
18. 18.587 − 267 =
19. 19.509 − 299 =
20. 20.725 − 497 =
21. 21.456 − 319 =
22. 22.564 − 198 =
23. 23.589 − 298 =
24. 24.553 − 528 =
25. 25.836 − 677 =
26. 26.781 − 439 =
27. 27.941 − 299 =
28. 28.807 − 498 =
29. 29.829 − 697 =
30. 30.715 − 329 =
31. 31.405 − 189 =
32. 32.907 − 497 =
33. 33.612 − 559 =
34. 34.603 − 498 =
35. 35.581 − 499 =
36. 36.628 − 548 =
37. 37.547 − 357 =
38. 38.935 − 219 =
39. 39.631 − 229 =
40. 40.717 − 519 =

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