Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 82 · 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. 1.617 − 477 =
2. 2.784 − 597 =
3. 3.531 − 419 =
4. 4.956 − 347 =
5. 5.858 − 598 =
6. 6.910 − 597 =
7. 7.327 − 198 =
8. 8.867 − 227 =
9. 9.550 − 457 =
10. 10.970 − 698 =
11. 11.548 − 258 =
12. 12.750 − 688 =
13. 13.525 − 297 =
14. 14.519 − 499 =
15. 15.742 − 238 =
16. 16.454 − 347 =
17. 17.949 − 698 =
18. 18.977 − 599 =
19. 19.679 − 397 =
20. 20.877 − 398 =
21. 21.647 − 599 =
22. 22.737 − 658 =
23. 23.459 − 198 =
24. 24.819 − 499 =
25. 25.874 − 477 =
26. 26.566 − 398 =
27. 27.902 − 797 =
28. 28.851 − 319 =
29. 29.782 − 399 =
30. 30.870 − 698 =
31. 31.553 − 297 =
32. 32.936 − 397 =
33. 33.729 − 129 =
34. 34.824 − 799 =
35. 35.619 − 439 =
36. 36.620 − 529 =
37. 37.872 − 598 =
38. 38.591 − 199 =
39. 39.571 − 397 =
40. 40.628 − 288 =

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