Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 998 · 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. 1.769 − 699 =
2. 2.333 − 277 =
3. 3.715 − 398 =
4. 4.731 − 598 =
5. 5.907 − 568 =
6. 6.907 − 199 =
7. 7.783 − 599 =
8. 8.634 − 148 =
9. 9.950 − 598 =
10. 10.727 − 399 =
11. 11.782 − 438 =
12. 12.782 − 629 =
13. 13.617 − 497 =
14. 14.232 − 199 =
15. 15.881 − 159 =
16. 16.846 − 497 =
17. 17.828 − 797 =
18. 18.413 − 247 =
19. 19.857 − 437 =
20. 20.259 − 199 =
21. 21.854 − 578 =
22. 22.854 − 597 =
23. 23.798 − 298 =
24. 24.795 − 299 =
25. 25.413 − 298 =
26. 26.483 − 297 =
27. 27.968 − 699 =
28. 28.941 − 498 =
29. 29.760 − 679 =
30. 30.928 − 158 =
31. 31.525 − 197 =
32. 32.647 − 139 =
33. 33.546 − 497 =
34. 34.749 − 288 =
35. 35.719 − 499 =
36. 36.184 − 149 =
37. 37.967 − 499 =
38. 38.700 − 399 =
39. 39.942 − 197 =
40. 40.383 − 199 =

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