Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 242 · 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. 1.873 − 799 =
2. 2.732 − 698 =
3. 3.266 − 199 =
4. 4.455 − 438 =
5. 5.954 − 798 =
6. 6.765 − 698 =
7. 7.874 − 799 =
8. 8.782 − 699 =
9. 9.572 − 199 =
10. 10.669 − 399 =
11. 11.462 − 248 =
12. 12.585 − 198 =
13. 13.569 − 467 =
14. 14.870 − 799 =
15. 15.821 − 497 =
16. 16.948 − 299 =
17. 17.668 − 299 =
18. 18.828 − 397 =
19. 19.934 − 558 =
20. 20.412 − 299 =
21. 21.686 − 127 =
22. 22.601 − 498 =
23. 23.692 − 597 =
24. 24.914 − 199 =
25. 25.956 − 437 =
26. 26.406 − 208 =
27. 27.611 − 469 =
28. 28.890 − 199 =
29. 29.426 − 127 =
30. 30.655 − 639 =
31. 31.967 − 548 =
32. 32.893 − 699 =
33. 33.625 − 299 =
34. 34.837 − 399 =
35. 35.898 − 298 =
36. 36.262 − 217 =
37. 37.970 − 599 =
38. 38.494 − 438 =
39. 39.863 − 797 =
40. 40.828 − 467 =

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