Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 591 · 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. 1.781 − 598 =
2. 2.984 − 599 =
3. 3.718 − 189 =
4. 4.794 − 369 =
5. 5.486 − 399 =
6. 6.307 − 248 =
7. 7.882 − 649 =
8. 8.863 − 699 =
9. 9.647 − 179 =
10. 10.225 − 199 =
11. 11.872 − 547 =
12. 12.705 − 597 =
13. 13.858 − 699 =
14. 14.866 − 397 =
15. 15.976 − 799 =
16. 16.880 − 479 =
17. 17.331 − 149 =
18. 18.938 − 498 =
19. 19.943 − 599 =
20. 20.984 − 198 =
21. 21.828 − 799 =
22. 22.815 − 209 =
23. 23.717 − 599 =
24. 24.733 − 678 =
25. 25.807 − 298 =
26. 26.745 − 597 =
27. 27.990 − 608 =
28. 28.966 − 679 =
29. 29.275 − 199 =
30. 30.928 − 698 =
31. 31.488 − 117 =
32. 32.697 − 299 =
33. 33.750 − 199 =
34. 34.748 − 698 =
35. 35.996 − 799 =
36. 36.953 − 318 =
37. 37.867 − 799 =
38. 38.765 − 498 =
39. 39.712 − 269 =
40. 40.740 − 697 =

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