Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 837 · 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. 1.635 − 139 =
2. 2.865 − 199 =
3. 3.800 − 499 =
4. 4.738 − 389 =
5. 5.560 − 478 =
6. 6.450 − 209 =
7. 7.917 − 179 =
8. 8.738 − 398 =
9. 9.712 − 697 =
10. 10.339 − 298 =
11. 11.441 − 299 =
12. 12.773 − 498 =
13. 13.881 − 799 =
14. 14.893 − 398 =
15. 15.466 − 297 =
16. 16.234 − 119 =
17. 17.852 − 798 =
18. 18.418 − 147 =
19. 19.759 − 417 =
20. 20.939 − 267 =
21. 21.571 − 259 =
22. 22.697 − 609 =
23. 23.973 − 197 =
24. 24.868 − 277 =
25. 25.988 − 499 =
26. 26.840 − 799 =
27. 27.736 − 297 =
28. 28.592 − 399 =
29. 29.329 − 198 =
30. 30.958 − 297 =
31. 31.830 − 797 =
32. 32.486 − 198 =
33. 33.820 − 797 =
34. 34.873 − 497 =
35. 35.979 − 259 =
36. 36.746 − 649 =
37. 37.882 − 588 =
38. 38.789 − 698 =
39. 39.653 − 627 =
40. 40.222 − 198 =

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