Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 507 · 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. 1.524 − 288 =
2. 2.256 − 199 =
3. 3.848 − 599 =
4. 4.936 − 597 =
5. 5.757 − 598 =
6. 6.738 − 217 =
7. 7.966 − 499 =
8. 8.726 − 397 =
9. 9.753 − 629 =
10. 10.930 − 498 =
11. 11.791 − 599 =
12. 12.639 − 397 =
13. 13.995 − 299 =
14. 14.881 − 798 =
15. 15.919 − 419 =
16. 16.505 − 468 =
17. 17.893 − 599 =
18. 18.783 − 689 =
19. 19.878 − 537 =
20. 20.399 − 248 =
21. 21.818 − 399 =
22. 22.955 − 508 =
23. 23.360 − 229 =
24. 24.234 − 218 =
25. 25.602 − 578 =
26. 26.347 − 299 =
27. 27.896 − 628 =
28. 28.980 − 697 =
29. 29.707 − 278 =
30. 30.627 − 378 =
31. 31.715 − 599 =
32. 32.750 − 699 =
33. 33.543 − 397 =
34. 34.710 − 599 =
35. 35.364 − 339 =
36. 36.604 − 248 =
37. 37.450 − 218 =
38. 38.973 − 799 =
39. 39.870 − 797 =
40. 40.945 − 629 =

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