Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 829 · 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. 1.728 − 399 =
2. 2.678 − 409 =
3. 3.736 − 599 =
4. 4.876 − 159 =
5. 5.484 − 247 =
6. 6.995 − 797 =
7. 7.802 − 397 =
8. 8.384 − 219 =
9. 9.910 − 697 =
10. 10.616 − 597 =
11. 11.761 − 619 =
12. 12.828 − 799 =
13. 13.292 − 209 =
14. 14.665 − 399 =
15. 15.633 − 199 =
16. 16.874 − 689 =
17. 17.675 − 127 =
18. 18.928 − 297 =
19. 19.668 − 299 =
20. 20.890 − 679 =
21. 21.920 − 699 =
22. 22.610 − 529 =
23. 23.817 − 799 =
24. 24.899 − 497 =
25. 25.866 − 699 =
26. 26.887 − 539 =
27. 27.868 − 798 =
28. 28.413 − 308 =
29. 29.772 − 358 =
30. 30.925 − 507 =
31. 31.406 − 217 =
32. 32.327 − 198 =
33. 33.850 − 697 =
34. 34.522 − 388 =
35. 35.209 − 157 =
36. 36.788 − 499 =
37. 37.421 − 228 =
38. 38.576 − 329 =
39. 39.671 − 297 =
40. 40.319 − 199 =

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