Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 171 · 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. 1.461 − 169 =
2. 2.817 − 297 =
3. 3.569 − 127 =
4. 4.952 − 357 =
5. 5.804 − 168 =
6. 6.421 − 297 =
7. 7.594 − 549 =
8. 8.971 − 799 =
9. 9.527 − 407 =
10. 10.507 − 189 =
11. 11.595 − 298 =
12. 12.849 − 457 =
13. 13.679 − 397 =
14. 14.992 − 797 =
15. 15.717 − 699 =
16. 16.816 − 698 =
17. 17.921 − 427 =
18. 18.601 − 447 =
19. 19.730 − 597 =
20. 20.763 − 698 =
21. 21.886 − 187 =
22. 22.495 − 119 =
23. 23.306 − 197 =
24. 24.678 − 607 =
25. 25.890 − 198 =
26. 26.693 − 199 =
27. 27.981 − 527 =
28. 28.808 − 598 =
29. 29.406 − 249 =
30. 30.932 − 398 =
31. 31.932 − 798 =
32. 32.578 − 299 =
33. 33.905 − 429 =
34. 34.784 − 487 =
35. 35.957 − 499 =
36. 36.963 − 698 =
37. 37.871 − 648 =
38. 38.884 − 698 =
39. 39.786 − 197 =
40. 40.835 − 799 =

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