Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 549 · 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. 1.761 − 299 =
2. 2.896 − 799 =
3. 3.698 − 597 =
4. 4.903 − 428 =
5. 5.820 − 699 =
6. 6.737 − 697 =
7. 7.786 − 498 =
8. 8.688 − 199 =
9. 9.697 − 497 =
10. 10.425 − 299 =
11. 11.816 − 498 =
12. 12.963 − 699 =
13. 13.868 − 668 =
14. 14.885 − 499 =
15. 15.919 − 698 =
16. 16.867 − 599 =
17. 17.774 − 698 =
18. 18.737 − 607 =
19. 19.593 − 297 =
20. 20.628 − 337 =
21. 21.944 − 368 =
22. 22.490 − 149 =
23. 23.963 − 149 =
24. 24.341 − 197 =
25. 25.692 − 199 =
26. 26.996 − 427 =
27. 27.979 − 597 =
28. 28.841 − 699 =
29. 29.844 − 469 =
30. 30.754 − 507 =
31. 31.630 − 298 =
32. 32.495 − 249 =
33. 33.532 − 298 =
34. 34.983 − 207 =
35. 35.870 − 498 =
36. 36.417 − 238 =
37. 37.776 − 199 =
38. 38.791 − 499 =
39. 39.922 − 499 =
40. 40.618 − 297 =

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