Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 1 · 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. 1.898 − 699 =
2. 2.879 − 798 =
3. 3.341 − 118 =
4. 4.707 − 328 =
5. 5.823 − 219 =
6. 6.945 − 189 =
7. 7.980 − 547 =
8. 8.897 − 797 =
9. 9.876 − 177 =
10. 10.491 − 427 =
11. 11.605 − 469 =
12. 12.820 − 279 =
13. 13.791 − 697 =
14. 14.780 − 298 =
15. 15.837 − 588 =
16. 16.785 − 597 =
17. 17.530 − 197 =
18. 18.354 − 199 =
19. 19.782 − 389 =
20. 20.621 − 499 =
21. 21.690 − 359 =
22. 22.836 − 698 =
23. 23.523 − 198 =
24. 24.920 − 378 =
25. 25.350 − 297 =
26. 26.356 − 237 =
27. 27.482 − 179 =
28. 28.774 − 698 =
29. 29.876 − 418 =
30. 30.759 − 227 =
31. 31.766 − 398 =
32. 32.564 − 208 =
33. 33.990 − 697 =
34. 34.919 − 228 =
35. 35.404 − 337 =
36. 36.578 − 227 =
37. 37.798 − 599 =
38. 38.648 − 619 =
39. 39.541 − 499 =
40. 40.808 − 697 =

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