Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 802 · 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. 1.929 − 597 =
2. 2.856 − 348 =
3. 3.252 − 139 =
4. 4.376 − 127 =
5. 5.665 − 227 =
6. 6.885 − 298 =
7. 7.800 − 138 =
8. 8.883 − 698 =
9. 9.968 − 799 =
10. 10.867 − 397 =
11. 11.723 − 399 =
12. 12.614 − 399 =
13. 13.884 − 599 =
14. 14.953 − 499 =
15. 15.956 − 689 =
16. 16.435 − 148 =
17. 17.407 − 259 =
18. 18.747 − 608 =
19. 19.815 − 798 =
20. 20.794 − 497 =
21. 21.590 − 168 =
22. 22.380 − 147 =
23. 23.399 − 268 =
24. 24.727 − 297 =
25. 25.767 − 598 =
26. 26.972 − 259 =
27. 27.694 − 397 =
28. 28.975 − 538 =
29. 29.734 − 298 =
30. 30.763 − 537 =
31. 31.333 − 199 =
32. 32.928 − 799 =
33. 33.831 − 797 =
34. 34.860 − 399 =
35. 35.470 − 437 =
36. 36.507 − 298 =
37. 37.433 − 399 =
38. 38.987 − 288 =
39. 39.752 − 299 =
40. 40.688 − 179 =

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