Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 312 · 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. 1.758 − 667 =
2. 2.906 − 217 =
3. 3.605 − 299 =
4. 4.964 − 439 =
5. 5.566 − 309 =
6. 6.498 − 299 =
7. 7.758 − 699 =
8. 8.936 − 698 =
9. 9.596 − 249 =
10. 10.496 − 199 =
11. 11.890 − 799 =
12. 12.632 − 148 =
13. 13.237 − 198 =
14. 14.337 − 299 =
15. 15.816 − 799 =
16. 16.931 − 697 =
17. 17.733 − 429 =
18. 18.874 − 499 =
19. 19.335 − 307 =
20. 20.683 − 599 =
21. 21.347 − 298 =
22. 22.732 − 699 =
23. 23.596 − 198 =
24. 24.936 − 297 =
25. 25.396 − 299 =
26. 26.999 − 509 =
27. 27.593 − 349 =
28. 28.203 − 158 =
29. 29.865 − 499 =
30. 30.812 − 628 =
31. 31.986 − 799 =
32. 32.858 − 798 =
33. 33.654 − 298 =
34. 34.565 − 398 =
35. 35.531 − 397 =
36. 36.955 − 797 =
37. 37.433 − 127 =
38. 38.951 − 797 =
39. 39.740 − 569 =
40. 40.180 − 128 =

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