Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 624 · 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. 1.914 − 257 =
2. 2.675 − 507 =
3. 3.730 − 698 =
4. 4.709 − 637 =
5. 5.929 − 497 =
6. 6.861 − 469 =
7. 7.635 − 177 =
8. 8.368 − 229 =
9. 9.892 − 697 =
10. 10.447 − 407 =
11. 11.871 − 189 =
12. 12.655 − 367 =
13. 13.622 − 197 =
14. 14.435 − 399 =
15. 15.797 − 199 =
16. 16.891 − 797 =
17. 17.766 − 479 =
18. 18.890 − 329 =
19. 19.832 − 697 =
20. 20.838 − 798 =
21. 21.432 − 199 =
22. 22.839 − 129 =
23. 23.274 − 199 =
24. 24.592 − 567 =
25. 25.462 − 367 =
26. 26.860 − 419 =
27. 27.624 − 598 =
28. 28.937 − 127 =
29. 29.526 − 449 =
30. 30.886 − 247 =
31. 31.663 − 398 =
32. 32.947 − 799 =
33. 33.927 − 559 =
34. 34.513 − 499 =
35. 35.619 − 287 =
36. 36.990 − 498 =
37. 37.657 − 399 =
38. 38.703 − 139 =
39. 39.797 − 198 =
40. 40.887 − 409 =

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