Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 561 · 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. 1.499 − 169 =
2. 2.932 − 448 =
3. 3.431 − 349 =
4. 4.748 − 299 =
5. 5.915 − 629 =
6. 6.585 − 398 =
7. 7.597 − 167 =
8. 8.416 − 369 =
9. 9.815 − 638 =
10. 10.580 − 447 =
11. 11.873 − 299 =
12. 12.549 − 358 =
13. 13.630 − 597 =
14. 14.890 − 497 =
15. 15.191 − 149 =
16. 16.399 − 128 =
17. 17.463 − 209 =
18. 18.932 − 797 =
19. 19.715 − 149 =
20. 20.838 − 329 =
21. 21.964 − 467 =
22. 22.904 − 597 =
23. 23.767 − 198 =
24. 24.778 − 698 =
25. 25.339 − 198 =
26. 26.754 − 689 =
27. 27.637 − 347 =
28. 28.642 − 239 =
29. 29.872 − 647 =
30. 30.795 − 599 =
31. 31.611 − 158 =
32. 32.728 − 189 =
33. 33.965 − 199 =
34. 34.819 − 297 =
35. 35.971 − 427 =
36. 36.872 − 227 =
37. 37.765 − 397 =
38. 38.569 − 459 =
39. 39.816 − 698 =
40. 40.979 − 138 =

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