Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 733 · 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. 1.870 − 798 =
2. 2.461 − 409 =
3. 3.420 − 169 =
4. 4.629 − 498 =
5. 5.836 − 798 =
6. 6.549 − 229 =
7. 7.629 − 199 =
8. 8.650 − 497 =
9. 9.807 − 199 =
10. 10.547 − 398 =
11. 11.598 − 399 =
12. 12.916 − 657 =
13. 13.540 − 298 =
14. 14.981 − 398 =
15. 15.845 − 598 =
16. 16.902 − 257 =
17. 17.773 − 658 =
18. 18.815 − 799 =
19. 19.610 − 527 =
20. 20.553 − 399 =
21. 21.829 − 597 =
22. 22.838 − 198 =
23. 23.798 − 297 =
24. 24.626 − 479 =
25. 25.305 − 198 =
26. 26.755 − 298 =
27. 27.747 − 597 =
28. 28.382 − 297 =
29. 29.724 − 539 =
30. 30.770 − 489 =
31. 31.935 − 798 =
32. 32.635 − 498 =
33. 33.580 − 498 =
34. 34.690 − 157 =
35. 35.797 − 488 =
36. 36.829 − 419 =
37. 37.449 − 197 =
38. 38.894 − 208 =
39. 39.814 − 699 =
40. 40.740 − 699 =

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