Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 503 · 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. 1.812 − 798 =
2. 2.909 − 197 =
3. 3.435 − 147 =
4. 4.357 − 299 =
5. 5.566 − 298 =
6. 6.813 − 797 =
7. 7.386 − 199 =
8. 8.806 − 378 =
9. 9.771 − 397 =
10. 10.496 − 298 =
11. 11.337 − 298 =
12. 12.727 − 448 =
13. 13.775 − 409 =
14. 14.717 − 597 =
15. 15.817 − 308 =
16. 16.487 − 399 =
17. 17.532 − 199 =
18. 18.906 − 577 =
19. 19.987 − 499 =
20. 20.867 − 797 =
21. 21.638 − 598 =
22. 22.596 − 448 =
23. 23.944 − 697 =
24. 24.866 − 697 =
25. 25.682 − 197 =
26. 26.856 − 398 =
27. 27.920 − 697 =
28. 28.965 − 569 =
29. 29.645 − 199 =
30. 30.762 − 378 =
31. 31.704 − 507 =
32. 32.747 − 497 =
33. 33.893 − 799 =
34. 34.593 − 277 =
35. 35.995 − 697 =
36. 36.409 − 289 =
37. 37.953 − 547 =
38. 38.662 − 638 =
39. 39.941 − 197 =
40. 40.997 − 597 =

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