Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 813 · 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. 1.903 − 368 =
2. 2.978 − 598 =
3. 3.568 − 499 =
4. 4.940 − 799 =
5. 5.794 − 377 =
6. 6.380 − 197 =
7. 7.868 − 349 =
8. 8.505 − 268 =
9. 9.741 − 697 =
10. 10.817 − 659 =
11. 11.680 − 228 =
12. 12.777 − 698 =
13. 13.772 − 298 =
14. 14.804 − 207 =
15. 15.796 − 597 =
16. 16.916 − 799 =
17. 17.482 − 299 =
18. 18.973 − 138 =
19. 19.384 − 198 =
20. 20.432 − 127 =
21. 21.630 − 197 =
22. 22.553 − 139 =
23. 23.172 − 127 =
24. 24.716 − 499 =
25. 25.772 − 198 =
26. 26.999 − 659 =
27. 27.854 − 408 =
28. 28.755 − 597 =
29. 29.883 − 699 =
30. 30.783 − 369 =
31. 31.779 − 697 =
32. 32.540 − 317 =
33. 33.858 − 798 =
34. 34.838 − 508 =
35. 35.841 − 599 =
36. 36.908 − 698 =
37. 37.586 − 297 =
38. 38.831 − 328 =
39. 39.397 − 209 =
40. 40.562 − 198 =

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