Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 407 · 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. 1.417 − 278 =
2. 2.607 − 298 =
3. 3.671 − 649 =
4. 4.950 − 797 =
5. 5.901 − 599 =
6. 6.909 − 799 =
7. 7.845 − 797 =
8. 8.716 − 699 =
9. 9.707 − 298 =
10. 10.715 − 429 =
11. 11.727 − 597 =
12. 12.607 − 139 =
13. 13.476 − 198 =
14. 14.965 − 507 =
15. 15.732 − 299 =
16. 16.969 − 698 =
17. 17.964 − 369 =
18. 18.670 − 499 =
19. 19.691 − 519 =
20. 20.758 − 499 =
21. 21.600 − 399 =
22. 22.838 − 237 =
23. 23.898 − 798 =
24. 24.449 − 297 =
25. 25.589 − 298 =
26. 26.503 − 299 =
27. 27.909 − 599 =
28. 28.622 − 437 =
29. 29.690 − 607 =
30. 30.363 − 198 =
31. 31.964 − 419 =
32. 32.526 − 298 =
33. 33.655 − 519 =
34. 34.485 − 208 =
35. 35.438 − 298 =
36. 36.634 − 497 =
37. 37.700 − 207 =
38. 38.559 − 198 =
39. 39.353 − 187 =
40. 40.630 − 549 =

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