Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 479 · 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. 1.480 − 398 =
2. 2.696 − 538 =
3. 3.667 − 399 =
4. 4.878 − 798 =
5. 5.658 − 117 =
6. 6.967 − 597 =
7. 7.730 − 509 =
8. 8.517 − 497 =
9. 9.573 − 497 =
10. 10.692 − 118 =
11. 11.706 − 367 =
12. 12.512 − 229 =
13. 13.921 − 698 =
14. 14.614 − 347 =
15. 15.922 − 599 =
16. 16.896 − 399 =
17. 17.929 − 217 =
18. 18.670 − 129 =
19. 19.938 − 798 =
20. 20.838 − 797 =
21. 21.941 − 398 =
22. 22.936 − 697 =
23. 23.753 − 337 =
24. 24.688 − 568 =
25. 25.950 − 599 =
26. 26.830 − 797 =
27. 27.852 − 399 =
28. 28.843 − 699 =
29. 29.935 − 308 =
30. 30.728 − 599 =
31. 31.800 − 458 =
32. 32.425 − 258 =
33. 33.964 − 399 =
34. 34.176 − 159 =
35. 35.835 − 397 =
36. 36.650 − 299 =
37. 37.995 − 697 =
38. 38.766 − 478 =
39. 39.912 − 398 =
40. 40.609 − 298 =

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