Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 759 · 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. 1.683 − 257 =
2. 2.379 − 199 =
3. 3.991 − 678 =
4. 4.966 − 417 =
5. 5.904 − 798 =
6. 6.972 − 519 =
7. 7.413 − 229 =
8. 8.977 − 438 =
9. 9.846 − 798 =
10. 10.895 − 257 =
11. 11.734 − 698 =
12. 12.863 − 599 =
13. 13.399 − 299 =
14. 14.588 − 399 =
15. 15.523 − 398 =
16. 16.948 − 497 =
17. 17.661 − 258 =
18. 18.520 − 497 =
19. 19.894 − 139 =
20. 20.405 − 338 =
21. 21.828 − 167 =
22. 22.723 − 497 =
23. 23.548 − 119 =
24. 24.949 − 799 =
25. 25.545 − 499 =
26. 26.914 − 229 =
27. 27.820 − 699 =
28. 28.724 − 698 =
29. 29.979 − 477 =
30. 30.802 − 199 =
31. 31.399 − 358 =
32. 32.674 − 597 =
33. 33.905 − 147 =
34. 34.974 − 697 =
35. 35.935 − 797 =
36. 36.698 − 499 =
37. 37.998 − 799 =
38. 38.469 − 398 =
39. 39.399 − 149 =
40. 40.821 − 498 =

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