Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 363 · 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. 1.600 − 187 =
2. 2.737 − 397 =
3. 3.543 − 398 =
4. 4.642 − 499 =
5. 5.790 − 597 =
6. 6.684 − 538 =
7. 7.535 − 297 =
8. 8.905 − 688 =
9. 9.607 − 208 =
10. 10.345 − 239 =
11. 11.614 − 199 =
12. 12.893 − 389 =
13. 13.998 − 627 =
14. 14.728 − 597 =
15. 15.998 − 298 =
16. 16.925 − 698 =
17. 17.815 − 198 =
18. 18.970 − 119 =
19. 19.340 − 209 =
20. 20.266 − 199 =
21. 21.776 − 598 =
22. 22.921 − 599 =
23. 23.743 − 599 =
24. 24.801 − 349 =
25. 25.654 − 598 =
26. 26.275 − 199 =
27. 27.659 − 397 =
28. 28.303 − 197 =
29. 29.608 − 399 =
30. 30.795 − 259 =
31. 31.395 − 299 =
32. 32.826 − 797 =
33. 33.373 − 149 =
34. 34.901 − 368 =
35. 35.833 − 799 =
36. 36.715 − 699 =
37. 37.860 − 659 =
38. 38.475 − 298 =
39. 39.711 − 198 =
40. 40.460 − 427 =

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