Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 863 · 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. 1.360 − 297 =
2. 2.760 − 297 =
3. 3.685 − 599 =
4. 4.940 − 507 =
5. 5.897 − 188 =
6. 6.607 − 549 =
7. 7.859 − 228 =
8. 8.761 − 648 =
9. 9.935 − 699 =
10. 10.733 − 697 =
11. 11.973 − 199 =
12. 12.628 − 197 =
13. 13.920 − 499 =
14. 14.957 − 387 =
15. 15.736 − 599 =
16. 16.996 − 289 =
17. 17.868 − 157 =
18. 18.483 − 288 =
19. 19.430 − 169 =
20. 20.967 − 609 =
21. 21.704 − 387 =
22. 22.433 − 298 =
23. 23.762 − 557 =
24. 24.250 − 198 =
25. 25.612 − 568 =
26. 26.917 − 267 =
27. 27.889 − 798 =
28. 28.812 − 658 =
29. 29.769 − 298 =
30. 30.839 − 289 =
31. 31.662 − 647 =
32. 32.580 − 397 =
33. 33.934 − 699 =
34. 34.689 − 598 =
35. 35.928 − 199 =
36. 36.470 − 429 =
37. 37.434 − 299 =
38. 38.752 − 397 =
39. 39.936 − 308 =
40. 40.886 − 659 =

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