Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 124 · 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. 1.561 − 499 =
2. 2.532 − 497 =
3. 3.378 − 198 =
4. 4.449 − 148 =
5. 5.986 − 797 =
6. 6.927 − 538 =
7. 7.807 − 398 =
8. 8.816 − 297 =
9. 9.871 − 297 =
10. 10.843 − 159 =
11. 11.886 − 429 =
12. 12.616 − 198 =
13. 13.697 − 668 =
14. 14.912 − 498 =
15. 15.396 − 258 =
16. 16.896 − 508 =
17. 17.871 − 398 =
18. 18.873 − 699 =
19. 19.720 − 599 =
20. 20.844 − 699 =
21. 21.913 − 799 =
22. 22.638 − 608 =
23. 23.830 − 297 =
24. 24.868 − 797 =
25. 25.732 − 278 =
26. 26.467 − 197 =
27. 27.876 − 699 =
28. 28.822 − 689 =
29. 29.836 − 698 =
30. 30.928 − 638 =
31. 31.198 − 177 =
32. 32.837 − 697 =
33. 33.968 − 697 =
34. 34.737 − 248 =
35. 35.674 − 299 =
36. 36.968 − 798 =
37. 37.695 − 299 =
38. 38.393 − 297 =
39. 39.774 − 587 =
40. 40.659 − 598 =

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