Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 68 · 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. 1.974 − 648 =
2. 2.510 − 398 =
3. 3.421 − 179 =
4. 4.373 − 237 =
5. 5.584 − 197 =
6. 6.797 − 669 =
7. 7.786 − 269 =
8. 8.977 − 797 =
9. 9.986 − 298 =
10. 10.296 − 197 =
11. 11.700 − 599 =
12. 12.855 − 597 =
13. 13.577 − 198 =
14. 14.812 − 497 =
15. 15.200 − 148 =
16. 16.644 − 399 =
17. 17.681 − 499 =
18. 18.834 − 498 =
19. 19.620 − 297 =
20. 20.755 − 289 =
21. 21.646 − 448 =
22. 22.410 − 267 =
23. 23.733 − 499 =
24. 24.829 − 569 =
25. 25.972 − 297 =
26. 26.846 − 697 =
27. 27.842 − 398 =
28. 28.719 − 599 =
29. 29.829 − 599 =
30. 30.800 − 199 =
31. 31.874 − 497 =
32. 32.693 − 308 =
33. 33.456 − 408 =
34. 34.692 − 637 =
35. 35.750 − 617 =
36. 36.879 − 697 =
37. 37.937 − 597 =
38. 38.419 − 198 =
39. 39.874 − 498 =
40. 40.455 − 269 =

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