Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 828 · 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. 1.730 − 199 =
2. 2.259 − 158 =
3. 3.729 − 627 =
4. 4.872 − 588 =
5. 5.632 − 198 =
6. 6.771 − 698 =
7. 7.831 − 698 =
8. 8.789 − 598 =
9. 9.873 − 798 =
10. 10.985 − 608 =
11. 11.613 − 438 =
12. 12.695 − 299 =
13. 13.381 − 297 =
14. 14.814 − 597 =
15. 15.804 − 197 =
16. 16.889 − 227 =
17. 17.942 − 519 =
18. 18.959 − 518 =
19. 19.682 − 397 =
20. 20.890 − 508 =
21. 21.803 − 509 =
22. 22.326 − 217 =
23. 23.952 − 298 =
24. 24.967 − 598 =
25. 25.906 − 197 =
26. 26.864 − 498 =
27. 27.927 − 297 =
28. 28.917 − 698 =
29. 29.728 − 228 =
30. 30.509 − 359 =
31. 31.543 − 297 =
32. 32.657 − 628 =
33. 33.892 − 309 =
34. 34.512 − 198 =
35. 35.942 − 798 =
36. 36.733 − 299 =
37. 37.308 − 197 =
38. 38.747 − 499 =
39. 39.548 − 498 =
40. 40.799 − 338 =

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