Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 328 · 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. 1.761 − 309 =
2. 2.977 − 408 =
3. 3.851 − 438 =
4. 4.358 − 179 =
5. 5.758 − 599 =
6. 6.435 − 269 =
7. 7.941 − 587 =
8. 8.427 − 198 =
9. 9.589 − 499 =
10. 10.510 − 328 =
11. 11.738 − 687 =
12. 12.711 − 397 =
13. 13.992 − 299 =
14. 14.795 − 198 =
15. 15.443 − 197 =
16. 16.375 − 299 =
17. 17.892 − 148 =
18. 18.916 − 339 =
19. 19.726 − 699 =
20. 20.921 − 398 =
21. 21.497 − 119 =
22. 22.747 − 267 =
23. 23.933 − 297 =
24. 24.843 − 619 =
25. 25.389 − 227 =
26. 26.931 − 599 =
27. 27.499 − 298 =
28. 28.838 − 597 =
29. 29.987 − 299 =
30. 30.925 − 479 =
31. 31.872 − 229 =
32. 32.919 − 699 =
33. 33.716 − 628 =
34. 34.750 − 497 =
35. 35.722 − 697 =
36. 36.571 − 518 =
37. 37.628 − 148 =
38. 38.964 − 597 =
39. 39.874 − 699 =
40. 40.848 − 419 =

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