Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 663 · 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. 1.435 − 199 =
2. 2.671 − 438 =
3. 3.880 − 317 =
4. 4.833 − 698 =
5. 5.910 − 398 =
6. 6.763 − 409 =
7. 7.339 − 299 =
8. 8.812 − 497 =
9. 9.836 − 598 =
10. 10.888 − 688 =
11. 11.995 − 798 =
12. 12.857 − 197 =
13. 13.856 − 209 =
14. 14.668 − 299 =
15. 15.715 − 337 =
16. 16.885 − 799 =
17. 17.410 − 297 =
18. 18.762 − 689 =
19. 19.247 − 209 =
20. 20.424 − 198 =
21. 21.815 − 218 =
22. 22.752 − 299 =
23. 23.231 − 147 =
24. 24.633 − 618 =
25. 25.370 − 167 =
26. 26.946 − 488 =
27. 27.523 − 397 =
28. 28.326 − 259 =
29. 29.553 − 159 =
30. 30.924 − 599 =
31. 31.979 − 319 =
32. 32.862 − 699 =
33. 33.383 − 267 =
34. 34.927 − 397 =
35. 35.771 − 199 =
36. 36.810 − 178 =
37. 37.639 − 138 =
38. 38.420 − 297 =
39. 39.920 − 589 =
40. 40.830 − 798 =

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