Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 457 · 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. 1.719 − 697 =
2. 2.574 − 549 =
3. 3.870 − 128 =
4. 4.898 − 797 =
5. 5.844 − 799 =
6. 6.587 − 229 =
7. 7.747 − 498 =
8. 8.732 − 698 =
9. 9.810 − 698 =
10. 10.937 − 499 =
11. 11.729 − 198 =
12. 12.706 − 619 =
13. 13.932 − 128 =
14. 14.443 − 359 =
15. 15.567 − 389 =
16. 16.660 − 597 =
17. 17.889 − 699 =
18. 18.349 − 299 =
19. 19.914 − 419 =
20. 20.747 − 699 =
21. 21.433 − 387 =
22. 22.698 − 578 =
23. 23.474 − 399 =
24. 24.766 − 699 =
25. 25.718 − 117 =
26. 26.256 − 167 =
27. 27.740 − 698 =
28. 28.814 − 599 =
29. 29.908 − 299 =
30. 30.955 − 399 =
31. 31.988 − 197 =
32. 32.954 − 557 =
33. 33.312 − 279 =
34. 34.988 − 498 =
35. 35.723 − 697 =
36. 36.923 − 428 =
37. 37.301 − 127 =
38. 38.451 − 397 =
39. 39.947 − 467 =
40. 40.695 − 598 =

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