Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 869 · 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. 1.454 − 139 =
2. 2.760 − 439 =
3. 3.899 − 699 =
4. 4.909 − 599 =
5. 5.548 − 159 =
6. 6.615 − 298 =
7. 7.696 − 297 =
8. 8.865 − 699 =
9. 9.260 − 199 =
10. 10.971 − 598 =
11. 11.624 − 179 =
12. 12.766 − 577 =
13. 13.507 − 397 =
14. 14.801 − 397 =
15. 15.672 − 578 =
16. 16.286 − 189 =
17. 17.572 − 337 =
18. 18.908 − 399 =
19. 19.554 − 497 =
20. 20.912 − 219 =
21. 21.671 − 599 =
22. 22.753 − 497 =
23. 23.393 − 258 =
24. 24.845 − 797 =
25. 25.790 − 678 =
26. 26.670 − 257 =
27. 27.510 − 398 =
28. 28.957 − 599 =
29. 29.999 − 178 =
30. 30.715 − 499 =
31. 31.745 − 127 =
32. 32.803 − 397 =
33. 33.630 − 497 =
34. 34.671 − 207 =
35. 35.485 − 197 =
36. 36.956 − 599 =
37. 37.657 − 197 =
38. 38.847 − 798 =
39. 39.504 − 399 =
40. 40.438 − 128 =

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