Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 641 · 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. 1.510 − 139 =
2. 2.617 − 598 =
3. 3.301 − 198 =
4. 4.802 − 618 =
5. 5.610 − 399 =
6. 6.494 − 208 =
7. 7.546 − 398 =
8. 8.479 − 298 =
9. 9.793 − 678 =
10. 10.885 − 298 =
11. 11.843 − 198 =
12. 12.607 − 339 =
13. 13.949 − 699 =
14. 14.757 − 679 =
15. 15.620 − 498 =
16. 16.827 − 799 =
17. 17.999 − 698 =
18. 18.453 − 309 =
19. 19.969 − 397 =
20. 20.867 − 339 =
21. 21.858 − 398 =
22. 22.791 − 699 =
23. 23.876 − 197 =
24. 24.894 − 469 =
25. 25.835 − 527 =
26. 26.894 − 597 =
27. 27.267 − 159 =
28. 28.815 − 598 =
29. 29.820 − 509 =
30. 30.885 − 598 =
31. 31.739 − 497 =
32. 32.688 − 598 =
33. 33.768 − 699 =
34. 34.712 − 598 =
35. 35.991 − 149 =
36. 36.596 − 159 =
37. 37.633 − 497 =
38. 38.807 − 579 =
39. 39.464 − 298 =
40. 40.814 − 797 =

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