Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 31 · 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 − 697 =
2. 2.979 − 478 =
3. 3.457 − 397 =
4. 4.971 − 269 =
5. 5.308 − 189 =
6. 6.995 − 637 =
7. 7.412 − 217 =
8. 8.610 − 137 =
9. 9.759 − 699 =
10. 10.697 − 668 =
11. 11.455 − 228 =
12. 12.785 − 297 =
13. 13.523 − 387 =
14. 14.916 − 199 =
15. 15.953 − 638 =
16. 16.776 − 197 =
17. 17.526 − 398 =
18. 18.367 − 239 =
19. 19.787 − 199 =
20. 20.614 − 467 =
21. 21.564 − 299 =
22. 22.974 − 199 =
23. 23.754 − 198 =
24. 24.866 − 689 =
25. 25.702 − 597 =
26. 26.819 − 797 =
27. 27.922 − 498 =
28. 28.743 − 498 =
29. 29.388 − 248 =
30. 30.371 − 299 =
31. 31.828 − 399 =
32. 32.931 − 697 =
33. 33.464 − 297 =
34. 34.795 − 137 =
35. 35.766 − 697 =
36. 36.741 − 698 =
37. 37.440 − 168 =
38. 38.824 − 798 =
39. 39.898 − 357 =
40. 40.769 − 198 =

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