Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 111 · 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. 1.789 − 398 =
2. 2.938 − 798 =
3. 3.986 − 799 =
4. 4.904 − 647 =
5. 5.976 − 599 =
6. 6.920 − 799 =
7. 7.786 − 588 =
8. 8.699 − 349 =
9. 9.551 − 457 =
10. 10.812 − 799 =
11. 11.848 − 499 =
12. 12.629 − 497 =
13. 13.483 − 129 =
14. 14.502 − 247 =
15. 15.228 − 198 =
16. 16.792 − 598 =
17. 17.824 − 608 =
18. 18.771 − 547 =
19. 19.388 − 299 =
20. 20.712 − 258 =
21. 21.894 − 698 =
22. 22.786 − 128 =
23. 23.574 − 499 =
24. 24.996 − 597 =
25. 25.944 − 517 =
26. 26.621 − 398 =
27. 27.543 − 299 =
28. 28.808 − 397 =
29. 29.859 − 499 =
30. 30.819 − 589 =
31. 31.260 − 199 =
32. 32.848 − 497 =
33. 33.227 − 159 =
34. 34.647 − 458 =
35. 35.317 − 197 =
36. 36.971 − 497 =
37. 37.599 − 197 =
38. 38.851 − 248 =
39. 39.440 − 197 =
40. 40.792 − 299 =

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