Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 17 · 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. 1.695 − 389 =
2. 2.819 − 697 =
3. 3.702 − 197 =
4. 4.477 − 297 =
5. 5.991 − 699 =
6. 6.627 − 197 =
7. 7.661 − 319 =
8. 8.952 − 499 =
9. 9.932 − 398 =
10. 10.881 − 577 =
11. 11.918 − 198 =
12. 12.372 − 199 =
13. 13.697 − 519 =
14. 14.336 − 288 =
15. 15.938 − 559 =
16. 16.940 − 298 =
17. 17.741 − 599 =
18. 18.752 − 577 =
19. 19.940 − 318 =
20. 20.769 − 699 =
21. 21.986 − 697 =
22. 22.789 − 117 =
23. 23.524 − 447 =
24. 24.639 − 297 =
25. 25.607 − 198 =
26. 26.998 − 499 =
27. 27.816 − 158 =
28. 28.394 − 158 =
29. 29.863 − 378 =
30. 30.707 − 138 =
31. 31.848 − 517 =
32. 32.804 − 597 =
33. 33.718 − 598 =
34. 34.585 − 228 =
35. 35.979 − 798 =
36. 36.365 − 189 =
37. 37.898 − 799 =
38. 38.956 − 697 =
39. 39.896 − 207 =
40. 40.931 − 697 =

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