Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 530 · 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. 1.989 − 447 =
2. 2.273 − 179 =
3. 3.606 − 498 =
4. 4.816 − 798 =
5. 5.637 − 248 =
6. 6.838 − 299 =
7. 7.840 − 329 =
8. 8.638 − 557 =
9. 9.579 − 418 =
10. 10.858 − 628 =
11. 11.789 − 298 =
12. 12.614 − 279 =
13. 13.568 − 199 =
14. 14.881 − 599 =
15. 15.907 − 698 =
16. 16.961 − 607 =
17. 17.967 − 798 =
18. 18.377 − 309 =
19. 19.852 − 179 =
20. 20.868 − 659 =
21. 21.731 − 199 =
22. 22.807 − 199 =
23. 23.843 − 437 =
24. 24.726 − 699 =
25. 25.505 − 398 =
26. 26.498 − 117 =
27. 27.416 − 197 =
28. 28.541 − 297 =
29. 29.804 − 399 =
30. 30.383 − 159 =
31. 31.901 − 699 =
32. 32.759 − 449 =
33. 33.896 − 797 =
34. 34.334 − 207 =
35. 35.774 − 607 =
36. 36.724 − 597 =
37. 37.649 − 587 =
38. 38.225 − 148 =
39. 39.607 − 527 =
40. 40.677 − 497 =

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