Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 677 · 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. 1.495 − 397 =
2. 2.913 − 798 =
3. 3.810 − 637 =
4. 4.850 − 299 =
5. 5.981 − 347 =
6. 6.505 − 389 =
7. 7.860 − 797 =
8. 8.745 − 659 =
9. 9.861 − 798 =
10. 10.786 − 497 =
11. 11.620 − 498 =
12. 12.904 − 597 =
13. 13.728 − 448 =
14. 14.950 − 277 =
15. 15.626 − 369 =
16. 16.254 − 198 =
17. 17.993 − 578 =
18. 18.986 − 698 =
19. 19.748 − 398 =
20. 20.628 − 167 =
21. 21.602 − 299 =
22. 22.808 − 519 =
23. 23.958 − 607 =
24. 24.878 − 677 =
25. 25.680 − 357 =
26. 26.677 − 187 =
27. 27.789 − 657 =
28. 28.402 − 197 =
29. 29.682 − 199 =
30. 30.758 − 597 =
31. 31.668 − 278 =
32. 32.670 − 598 =
33. 33.562 − 399 =
34. 34.796 − 597 =
35. 35.812 − 549 =
36. 36.564 − 399 =
37. 37.273 − 198 =
38. 38.534 − 199 =
39. 39.221 − 127 =
40. 40.995 − 637 =

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