Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 967 · 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. 1.808 − 399 =
2. 2.685 − 498 =
3. 3.953 − 599 =
4. 4.777 − 297 =
5. 5.586 − 357 =
6. 6.957 − 579 =
7. 7.712 − 679 =
8. 8.826 − 417 =
9. 9.581 − 198 =
10. 10.812 − 598 =
11. 11.999 − 299 =
12. 12.139 − 117 =
13. 13.960 − 297 =
14. 14.680 − 398 =
15. 15.793 − 368 =
16. 16.876 − 299 =
17. 17.755 − 698 =
18. 18.208 − 118 =
19. 19.883 − 697 =
20. 20.212 − 147 =
21. 21.501 − 278 =
22. 22.864 − 598 =
23. 23.927 − 799 =
24. 24.615 − 407 =
25. 25.873 − 558 =
26. 26.887 − 597 =
27. 27.976 − 647 =
28. 28.717 − 638 =
29. 29.951 − 499 =
30. 30.391 − 198 =
31. 31.939 − 798 =
32. 32.826 − 697 =
33. 33.441 − 298 =
34. 34.619 − 318 =
35. 35.767 − 319 =
36. 36.695 − 498 =
37. 37.556 − 397 =
38. 38.577 − 499 =
39. 39.869 − 298 =
40. 40.987 − 599 =

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