Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 638 · 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. 1.732 − 598 =
2. 2.618 − 219 =
3. 3.839 − 799 =
4. 4.983 − 197 =
5. 5.650 − 399 =
6. 6.681 − 398 =
7. 7.897 − 798 =
8. 8.535 − 407 =
9. 9.809 − 409 =
10. 10.844 − 797 =
11. 11.869 − 628 =
12. 12.404 − 139 =
13. 13.812 − 297 =
14. 14.191 − 147 =
15. 15.498 − 197 =
16. 16.634 − 198 =
17. 17.574 − 278 =
18. 18.650 − 497 =
19. 19.756 − 528 =
20. 20.551 − 258 =
21. 21.958 − 799 =
22. 22.963 − 499 =
23. 23.563 − 348 =
24. 24.665 − 499 =
25. 25.482 − 398 =
26. 26.796 − 197 =
27. 27.622 − 589 =
28. 28.804 − 448 =
29. 29.678 − 608 =
30. 30.416 − 199 =
31. 31.606 − 499 =
32. 32.323 − 298 =
33. 33.943 − 579 =
34. 34.934 − 399 =
35. 35.635 − 597 =
36. 36.602 − 299 =
37. 37.709 − 619 =
38. 38.824 − 497 =
39. 39.601 − 298 =
40. 40.673 − 498 =

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