Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 993 · 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. 1.799 − 699 =
2. 2.904 − 797 =
3. 3.837 − 797 =
4. 4.697 − 269 =
5. 5.688 − 297 =
6. 6.471 − 217 =
7. 7.912 − 598 =
8. 8.670 − 599 =
9. 9.945 − 538 =
10. 10.457 − 299 =
11. 11.867 − 647 =
12. 12.525 − 499 =
13. 13.606 − 398 =
14. 14.837 − 799 =
15. 15.641 − 498 =
16. 16.802 − 659 =
17. 17.830 − 569 =
18. 18.572 − 499 =
19. 19.693 − 497 =
20. 20.649 − 619 =
21. 21.289 − 198 =
22. 22.823 − 638 =
23. 23.726 − 228 =
24. 24.877 − 197 =
25. 25.427 − 399 =
26. 26.544 − 408 =
27. 27.465 − 399 =
28. 28.336 − 127 =
29. 29.989 − 197 =
30. 30.944 − 198 =
31. 31.862 − 699 =
32. 32.815 − 799 =
33. 33.816 − 198 =
34. 34.657 − 499 =
35. 35.628 − 597 =
36. 36.257 − 158 =
37. 37.423 − 199 =
38. 38.428 − 148 =
39. 39.785 − 579 =
40. 40.419 − 307 =

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