Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 581 · 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. 1.653 − 509 =
2. 2.915 − 197 =
3. 3.655 − 467 =
4. 4.397 − 297 =
5. 5.528 − 498 =
6. 6.507 − 297 =
7. 7.842 − 588 =
8. 8.973 − 197 =
9. 9.801 − 498 =
10. 10.517 − 298 =
11. 11.315 − 299 =
12. 12.969 − 599 =
13. 13.532 − 197 =
14. 14.802 − 298 =
15. 15.848 − 398 =
16. 16.646 − 597 =
17. 17.751 − 199 =
18. 18.926 − 608 =
19. 19.529 − 259 =
20. 20.885 − 579 =
21. 21.883 − 579 =
22. 22.961 − 599 =
23. 23.836 − 308 =
24. 24.953 − 148 =
25. 25.779 − 287 =
26. 26.604 − 497 =
27. 27.737 − 699 =
28. 28.605 − 159 =
29. 29.359 − 198 =
30. 30.951 − 397 =
31. 31.730 − 198 =
32. 32.894 − 569 =
33. 33.984 − 258 =
34. 34.826 − 498 =
35. 35.382 − 299 =
36. 36.692 − 297 =
37. 37.899 − 598 =
38. 38.720 − 317 =
39. 39.737 − 197 =
40. 40.754 − 159 =

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