Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 572 · 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. 1.246 − 129 =
2. 2.842 − 299 =
3. 3.845 − 798 =
4. 4.769 − 639 =
5. 5.862 − 597 =
6. 6.881 − 118 =
7. 7.636 − 597 =
8. 8.871 − 398 =
9. 9.886 − 399 =
10. 10.721 − 698 =
11. 11.431 − 257 =
12. 12.356 − 149 =
13. 13.869 − 798 =
14. 14.818 − 697 =
15. 15.910 − 499 =
16. 16.761 − 197 =
17. 17.871 − 389 =
18. 18.350 − 297 =
19. 19.534 − 338 =
20. 20.954 − 368 =
21. 21.815 − 298 =
22. 22.734 − 398 =
23. 23.445 − 198 =
24. 24.948 − 699 =
25. 25.716 − 599 =
26. 26.791 − 298 =
27. 27.902 − 799 =
28. 28.873 − 398 =
29. 29.828 − 459 =
30. 30.844 − 118 =
31. 31.748 − 399 =
32. 32.445 − 199 =
33. 33.993 − 799 =
34. 34.967 − 567 =
35. 35.501 − 217 =
36. 36.585 − 499 =
37. 37.456 − 397 =
38. 38.245 − 149 =
39. 39.721 − 397 =
40. 40.757 − 638 =

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