Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 324 · 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. 1.938 − 797 =
2. 2.906 − 457 =
3. 3.988 − 179 =
4. 4.778 − 388 =
5. 5.579 − 299 =
6. 6.897 − 297 =
7. 7.946 − 559 =
8. 8.748 − 697 =
9. 9.248 − 197 =
10. 10.793 − 399 =
11. 11.943 − 797 =
12. 12.699 − 499 =
13. 13.887 − 499 =
14. 14.946 − 398 =
15. 15.781 − 599 =
16. 16.552 − 497 =
17. 17.832 − 697 =
18. 18.854 − 397 =
19. 19.716 − 159 =
20. 20.880 − 597 =
21. 21.633 − 159 =
22. 22.337 − 297 =
23. 23.684 − 647 =
24. 24.356 − 269 =
25. 25.959 − 609 =
26. 26.731 − 697 =
27. 27.995 − 299 =
28. 28.736 − 608 =
29. 29.697 − 659 =
30. 30.553 − 499 =
31. 31.970 − 197 =
32. 32.619 − 497 =
33. 33.567 − 499 =
34. 34.946 − 508 =
35. 35.602 − 448 =
36. 36.716 − 397 =
37. 37.765 − 369 =
38. 38.574 − 498 =
39. 39.976 − 799 =
40. 40.646 − 198 =

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