Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 942 · 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. 1.821 − 399 =
2. 2.987 − 598 =
3. 3.314 − 297 =
4. 4.762 − 699 =
5. 5.456 − 397 =
6. 6.645 − 198 =
7. 7.699 − 679 =
8. 8.855 − 297 =
9. 9.985 − 249 =
10. 10.572 − 297 =
11. 11.637 − 597 =
12. 12.974 − 687 =
13. 13.644 − 288 =
14. 14.724 − 648 =
15. 15.838 − 298 =
16. 16.399 − 198 =
17. 17.875 − 327 =
18. 18.861 − 198 =
19. 19.864 − 399 =
20. 20.763 − 459 =
21. 21.415 − 299 =
22. 22.925 − 797 =
23. 23.959 − 799 =
24. 24.343 − 299 =
25. 25.494 − 399 =
26. 26.339 − 199 =
27. 27.897 − 467 =
28. 28.660 − 179 =
29. 29.969 − 198 =
30. 30.684 − 199 =
31. 31.725 − 177 =
32. 32.751 − 557 =
33. 33.733 − 699 =
34. 34.824 − 548 =
35. 35.798 − 158 =
36. 36.768 − 407 =
37. 37.930 − 199 =
38. 38.191 − 168 =
39. 39.983 − 397 =
40. 40.979 − 297 =

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