Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 660 · 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. 1.840 − 699 =
2. 2.350 − 268 =
3. 3.967 − 447 =
4. 4.843 − 647 =
5. 5.651 − 587 =
6. 6.905 − 298 =
7. 7.606 − 397 =
8. 8.913 − 797 =
9. 9.813 − 567 =
10. 10.880 − 667 =
11. 11.391 − 217 =
12. 12.754 − 697 =
13. 13.740 − 498 =
14. 14.995 − 297 =
15. 15.713 − 589 =
16. 16.499 − 358 =
17. 17.759 − 398 =
18. 18.903 − 799 =
19. 19.898 − 698 =
20. 20.935 − 699 =
21. 21.864 − 387 =
22. 22.922 − 399 =
23. 23.649 − 397 =
24. 24.559 − 398 =
25. 25.822 − 699 =
26. 26.956 − 517 =
27. 27.642 − 127 =
28. 28.735 − 498 =
29. 29.883 − 797 =
30. 30.976 − 499 =
31. 31.699 − 267 =
32. 32.981 − 797 =
33. 33.955 − 377 =
34. 34.969 − 377 =
35. 35.868 − 698 =
36. 36.928 − 177 =
37. 37.820 − 299 =
38. 38.712 − 267 =
39. 39.494 − 159 =
40. 40.361 − 298 =

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