Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 370 · 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. 1.882 − 698 =
2. 2.905 − 618 =
3. 3.556 − 397 =
4. 4.536 − 297 =
5. 5.501 − 298 =
6. 6.517 − 199 =
7. 7.988 − 797 =
8. 8.410 − 227 =
9. 9.413 − 299 =
10. 10.628 − 578 =
11. 11.985 − 597 =
12. 12.597 − 499 =
13. 13.426 − 299 =
14. 14.666 − 497 =
15. 15.647 − 399 =
16. 16.693 − 498 =
17. 17.511 − 299 =
18. 18.910 − 599 =
19. 19.657 − 398 =
20. 20.929 − 798 =
21. 21.386 − 297 =
22. 22.533 − 499 =
23. 23.992 − 698 =
24. 24.764 − 198 =
25. 25.850 − 799 =
26. 26.868 − 597 =
27. 27.796 − 158 =
28. 28.898 − 449 =
29. 29.599 − 459 =
30. 30.845 − 297 =
31. 31.412 − 197 =
32. 32.832 − 507 =
33. 33.904 − 697 =
34. 34.965 − 697 =
35. 35.868 − 299 =
36. 36.839 − 468 =
37. 37.505 − 399 =
38. 38.925 − 799 =
39. 39.343 − 259 =
40. 40.413 − 138 =

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