Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 628 · 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. 1.547 − 398 =
2. 2.944 − 798 =
3. 3.513 − 298 =
4. 4.683 − 297 =
5. 5.536 − 399 =
6. 6.657 − 497 =
7. 7.682 − 198 =
8. 8.945 − 197 =
9. 9.816 − 799 =
10. 10.788 − 479 =
11. 11.581 − 469 =
12. 12.403 − 298 =
13. 13.360 − 297 =
14. 14.777 − 699 =
15. 15.764 − 299 =
16. 16.483 − 299 =
17. 17.729 − 698 =
18. 18.690 − 578 =
19. 19.968 − 619 =
20. 20.884 − 797 =
21. 21.885 − 197 =
22. 22.749 − 399 =
23. 23.910 − 398 =
24. 24.496 − 297 =
25. 25.829 − 799 =
26. 26.721 − 398 =
27. 27.808 − 398 =
28. 28.931 − 687 =
29. 29.774 − 298 =
30. 30.617 − 278 =
31. 31.735 − 137 =
32. 32.760 − 167 =
33. 33.852 − 799 =
34. 34.708 − 499 =
35. 35.382 − 157 =
36. 36.820 − 269 =
37. 37.707 − 397 =
38. 38.985 − 297 =
39. 39.763 − 179 =
40. 40.944 − 608 =

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