Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 830 · 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. 1.912 − 419 =
2. 2.731 − 687 =
3. 3.212 − 198 =
4. 4.865 − 498 =
5. 5.622 − 597 =
6. 6.735 − 599 =
7. 7.433 − 198 =
8. 8.584 − 377 =
9. 9.740 − 357 =
10. 10.943 − 199 =
11. 11.584 − 298 =
12. 12.971 − 349 =
13. 13.703 − 388 =
14. 14.604 − 199 =
15. 15.614 − 199 =
16. 16.790 − 319 =
17. 17.566 − 419 =
18. 18.690 − 649 =
19. 19.942 − 297 =
20. 20.590 − 199 =
21. 21.739 − 297 =
22. 22.992 − 798 =
23. 23.712 − 298 =
24. 24.700 − 529 =
25. 25.959 − 549 =
26. 26.715 − 588 =
27. 27.850 − 599 =
28. 28.381 − 297 =
29. 29.971 − 199 =
30. 30.855 − 299 =
31. 31.909 − 199 =
32. 32.576 − 127 =
33. 33.455 − 399 =
34. 34.780 − 197 =
35. 35.394 − 299 =
36. 36.948 − 699 =
37. 37.497 − 297 =
38. 38.497 − 367 =
39. 39.811 − 679 =
40. 40.716 − 519 =

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