Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 354 · 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. 1.505 − 398 =
2. 2.690 − 398 =
3. 3.930 − 398 =
4. 4.954 − 497 =
5. 5.635 − 199 =
6. 6.592 − 499 =
7. 7.823 − 457 =
8. 8.870 − 288 =
9. 9.897 − 347 =
10. 10.560 − 427 =
11. 11.816 − 799 =
12. 12.489 − 267 =
13. 13.465 − 289 =
14. 14.669 − 598 =
15. 15.631 − 598 =
16. 16.828 − 798 =
17. 17.846 − 659 =
18. 18.957 − 499 =
19. 19.806 − 419 =
20. 20.334 − 297 =
21. 21.794 − 557 =
22. 22.709 − 279 =
23. 23.772 − 698 =
24. 24.820 − 497 =
25. 25.802 − 298 =
26. 26.677 − 497 =
27. 27.849 − 799 =
28. 28.452 − 269 =
29. 29.645 − 199 =
30. 30.524 − 448 =
31. 31.999 − 799 =
32. 32.936 − 658 =
33. 33.868 − 797 =
34. 34.926 − 117 =
35. 35.837 − 698 =
36. 36.915 − 338 =
37. 37.613 − 507 =
38. 38.698 − 199 =
39. 39.804 − 299 =
40. 40.738 − 297 =

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