Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 960 · 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. 1.529 − 298 =
2. 2.991 − 798 =
3. 3.902 − 698 =
4. 4.228 − 129 =
5. 5.776 − 697 =
6. 6.429 − 188 =
7. 7.860 − 257 =
8. 8.639 − 497 =
9. 9.990 − 199 =
10. 10.923 − 798 =
11. 11.767 − 697 =
12. 12.730 − 599 =
13. 13.560 − 399 =
14. 14.957 − 499 =
15. 15.616 − 338 =
16. 16.867 − 599 =
17. 17.677 − 297 =
18. 18.613 − 597 =
19. 19.921 − 797 =
20. 20.550 − 197 =
21. 21.465 − 139 =
22. 22.673 − 297 =
23. 23.804 − 148 =
24. 24.574 − 427 =
25. 25.317 − 227 =
26. 26.668 − 499 =
27. 27.904 − 399 =
28. 28.510 − 297 =
29. 29.823 − 698 =
30. 30.699 − 648 =
31. 31.902 − 597 =
32. 32.593 − 199 =
33. 33.754 − 199 =
34. 34.612 − 287 =
35. 35.853 − 548 =
36. 36.681 − 387 =
37. 37.506 − 299 =
38. 38.818 − 297 =
39. 39.732 − 587 =
40. 40.634 − 339 =

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