Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 2 · 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. 1.831 − 497 =
2. 2.979 − 798 =
3. 3.586 − 198 =
4. 4.794 − 499 =
5. 5.880 − 689 =
6. 6.490 − 128 =
7. 7.874 − 197 =
8. 8.762 − 199 =
9. 9.661 − 498 =
10. 10.578 − 398 =
11. 11.790 − 637 =
12. 12.828 − 657 =
13. 13.905 − 599 =
14. 14.631 − 447 =
15. 15.991 − 298 =
16. 16.829 − 699 =
17. 17.829 − 597 =
18. 18.479 − 297 =
19. 19.505 − 398 =
20. 20.805 − 599 =
21. 21.716 − 269 =
22. 22.389 − 197 =
23. 23.937 − 268 =
24. 24.509 − 468 =
25. 25.810 − 299 =
26. 26.619 − 558 =
27. 27.473 − 388 =
28. 28.915 − 799 =
29. 29.712 − 199 =
30. 30.530 − 499 =
31. 31.910 − 498 =
32. 32.745 − 459 =
33. 33.371 − 299 =
34. 34.758 − 639 =
35. 35.842 − 798 =
36. 36.694 − 578 =
37. 37.944 − 798 =
38. 38.399 − 197 =
39. 39.679 − 468 =
40. 40.694 − 568 =

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