Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 251 · 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. 1.328 − 199 =
2. 2.863 − 198 =
3. 3.597 − 397 =
4. 4.471 − 198 =
5. 5.594 − 398 =
6. 6.324 − 209 =
7. 7.420 − 299 =
8. 8.926 − 139 =
9. 9.995 − 258 =
10. 10.861 − 698 =
11. 11.973 − 668 =
12. 12.813 − 168 =
13. 13.985 − 599 =
14. 14.703 − 198 =
15. 15.608 − 247 =
16. 16.509 − 409 =
17. 17.447 − 298 =
18. 18.571 − 399 =
19. 19.985 − 387 =
20. 20.898 − 549 =
21. 21.949 − 279 =
22. 22.678 − 398 =
23. 23.967 − 597 =
24. 24.799 − 169 =
25. 25.923 − 648 =
26. 26.754 − 699 =
27. 27.485 − 458 =
28. 28.987 − 499 =
29. 29.844 − 399 =
30. 30.685 − 498 =
31. 31.985 − 499 =
32. 32.497 − 198 =
33. 33.736 − 598 =
34. 34.769 − 698 =
35. 35.664 − 399 =
36. 36.876 − 799 =
37. 37.461 − 199 =
38. 38.638 − 199 =
39. 39.830 − 297 =
40. 40.952 − 638 =

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