Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 982 · 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. 1.770 − 258 =
2. 2.624 − 598 =
3. 3.385 − 117 =
4. 4.764 − 209 =
5. 5.533 − 129 =
6. 6.763 − 699 =
7. 7.862 − 698 =
8. 8.637 − 399 =
9. 9.908 − 599 =
10. 10.552 − 398 =
11. 11.899 − 697 =
12. 12.896 − 198 =
13. 13.395 − 198 =
14. 14.994 − 228 =
15. 15.735 − 598 =
16. 16.869 − 407 =
17. 17.902 − 217 =
18. 18.758 − 178 =
19. 19.608 − 398 =
20. 20.763 − 299 =
21. 21.846 − 299 =
22. 22.908 − 489 =
23. 23.682 − 347 =
24. 24.713 − 409 =
25. 25.633 − 297 =
26. 26.744 − 598 =
27. 27.562 − 178 =
28. 28.759 − 697 =
29. 29.455 − 398 =
30. 30.963 − 798 =
31. 31.595 − 449 =
32. 32.941 − 797 =
33. 33.893 − 798 =
34. 34.831 − 397 =
35. 35.654 − 597 =
36. 36.618 − 297 =
37. 37.430 − 118 =
38. 38.979 − 688 =
39. 39.626 − 198 =
40. 40.944 − 699 =

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