Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 65 · 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. 1.824 − 799 =
2. 2.372 − 197 =
3. 3.866 − 798 =
4. 4.860 − 229 =
5. 5.681 − 509 =
6. 6.216 − 197 =
7. 7.348 − 118 =
8. 8.854 − 798 =
9. 9.939 − 508 =
10. 10.658 − 597 =
11. 11.998 − 648 =
12. 12.973 − 799 =
13. 13.381 − 138 =
14. 14.774 − 598 =
15. 15.764 − 699 =
16. 16.349 − 117 =
17. 17.658 − 557 =
18. 18.920 − 498 =
19. 19.940 − 397 =
20. 20.496 − 409 =
21. 21.970 − 597 =
22. 22.880 − 799 =
23. 23.834 − 649 =
24. 24.736 − 388 =
25. 25.675 − 447 =
26. 26.308 − 117 =
27. 27.278 − 198 =
28. 28.860 − 598 =
29. 29.917 − 198 =
30. 30.832 − 399 =
31. 31.940 − 698 =
32. 32.467 − 398 =
33. 33.274 − 119 =
34. 34.796 − 488 =
35. 35.759 − 499 =
36. 36.996 − 198 =
37. 37.913 − 117 =
38. 38.681 − 429 =
39. 39.942 − 697 =
40. 40.905 − 559 =

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