Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 840 · 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. 1.523 − 497 =
2. 2.668 − 179 =
3. 3.796 − 427 =
4. 4.962 − 798 =
5. 5.825 − 199 =
6. 6.409 − 199 =
7. 7.360 − 138 =
8. 8.798 − 448 =
9. 9.474 − 398 =
10. 10.617 − 337 =
11. 11.879 − 699 =
12. 12.697 − 199 =
13. 13.523 − 197 =
14. 14.747 − 149 =
15. 15.809 − 697 =
16. 16.750 − 457 =
17. 17.598 − 497 =
18. 18.860 − 157 =
19. 19.753 − 597 =
20. 20.836 − 797 =
21. 21.926 − 799 =
22. 22.326 − 238 =
23. 23.833 − 267 =
24. 24.563 − 228 =
25. 25.525 − 168 =
26. 26.988 − 599 =
27. 27.490 − 207 =
28. 28.906 − 297 =
29. 29.444 − 398 =
30. 30.707 − 439 =
31. 31.912 − 598 =
32. 32.784 − 419 =
33. 33.920 − 298 =
34. 34.620 − 297 =
35. 35.962 − 799 =
36. 36.785 − 548 =
37. 37.631 − 487 =
38. 38.787 − 687 =
39. 39.839 − 497 =
40. 40.340 − 248 =

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