Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 399 · 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. 1.404 − 258 =
2. 2.954 − 457 =
3. 3.665 − 297 =
4. 4.973 − 577 =
5. 5.700 − 497 =
6. 6.701 − 197 =
7. 7.864 − 798 =
8. 8.928 − 698 =
9. 9.526 − 377 =
10. 10.326 − 197 =
11. 11.315 − 198 =
12. 12.900 − 499 =
13. 13.642 − 299 =
14. 14.921 − 199 =
15. 15.778 − 599 =
16. 16.569 − 248 =
17. 17.659 − 498 =
18. 18.328 − 299 =
19. 19.672 − 287 =
20. 20.598 − 117 =
21. 21.647 − 498 =
22. 22.754 − 599 =
23. 23.635 − 349 =
24. 24.774 − 237 =
25. 25.345 − 258 =
26. 26.874 − 507 =
27. 27.684 − 199 =
28. 28.458 − 168 =
29. 29.964 − 297 =
30. 30.713 − 529 =
31. 31.978 − 699 =
32. 32.413 − 168 =
33. 33.723 − 697 =
34. 34.971 − 167 =
35. 35.822 − 497 =
36. 36.859 − 799 =
37. 37.934 − 609 =
38. 38.285 − 128 =
39. 39.933 − 597 =
40. 40.911 − 398 =

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