Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 831 · 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. 1.697 − 578 =
2. 2.886 − 699 =
3. 3.845 − 368 =
4. 4.543 − 197 =
5. 5.302 − 277 =
6. 6.790 − 219 =
7. 7.652 − 599 =
8. 8.860 − 597 =
9. 9.945 − 168 =
10. 10.786 − 577 =
11. 11.984 − 279 =
12. 12.700 − 187 =
13. 13.672 − 599 =
14. 14.634 − 597 =
15. 15.444 − 418 =
16. 16.850 − 127 =
17. 17.955 − 658 =
18. 18.622 − 527 =
19. 19.897 − 569 =
20. 20.654 − 569 =
21. 21.790 − 697 =
22. 22.929 − 298 =
23. 23.421 − 187 =
24. 24.652 − 639 =
25. 25.989 − 298 =
26. 26.727 − 597 =
27. 27.757 − 268 =
28. 28.831 − 297 =
29. 29.828 − 649 =
30. 30.353 − 298 =
31. 31.971 − 397 =
32. 32.910 − 559 =
33. 33.846 − 167 =
34. 34.837 − 427 =
35. 35.530 − 427 =
36. 36.521 − 397 =
37. 37.978 − 199 =
38. 38.970 − 148 =
39. 39.867 − 158 =
40. 40.999 − 499 =

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