Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 898 · 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. 1.820 − 597 =
2. 2.823 − 498 =
3. 3.731 − 498 =
4. 4.520 − 498 =
5. 5.995 − 599 =
6. 6.925 − 448 =
7. 7.910 − 339 =
8. 8.993 − 598 =
9. 9.365 − 298 =
10. 10.370 − 339 =
11. 11.835 − 799 =
12. 12.656 − 299 =
13. 13.667 − 598 =
14. 14.888 − 699 =
15. 15.520 − 467 =
16. 16.985 − 798 =
17. 17.976 − 399 =
18. 18.772 − 398 =
19. 19.872 − 617 =
20. 20.926 − 427 =
21. 21.467 − 167 =
22. 22.654 − 529 =
23. 23.479 − 398 =
24. 24.187 − 137 =
25. 25.761 − 699 =
26. 26.439 − 298 =
27. 27.895 − 799 =
28. 28.724 − 527 =
29. 29.781 − 497 =
30. 30.692 − 599 =
31. 31.759 − 399 =
32. 32.481 − 397 =
33. 33.904 − 497 =
34. 34.951 − 799 =
35. 35.694 − 547 =
36. 36.300 − 228 =
37. 37.784 − 298 =
38. 38.756 − 398 =
39. 39.962 − 797 =
40. 40.664 − 539 =

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