Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 554 · 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. 1.525 − 468 =
2. 2.914 − 498 =
3. 3.447 − 298 =
4. 4.915 − 799 =
5. 5.609 − 117 =
6. 6.507 − 199 =
7. 7.546 − 317 =
8. 8.671 − 238 =
9. 9.669 − 398 =
10. 10.614 − 197 =
11. 11.767 − 199 =
12. 12.775 − 569 =
13. 13.616 − 599 =
14. 14.658 − 498 =
15. 15.864 − 797 =
16. 16.466 − 299 =
17. 17.505 − 469 =
18. 18.806 − 249 =
19. 19.944 − 297 =
20. 20.411 − 347 =
21. 21.836 − 499 =
22. 22.858 − 607 =
23. 23.969 − 419 =
24. 24.946 − 327 =
25. 25.838 − 698 =
26. 26.744 − 597 =
27. 27.749 − 698 =
28. 28.917 − 197 =
29. 29.639 − 499 =
30. 30.507 − 459 =
31. 31.753 − 179 =
32. 32.908 − 198 =
33. 33.483 − 407 =
34. 34.604 − 499 =
35. 35.456 − 218 =
36. 36.875 − 799 =
37. 37.447 − 138 =
38. 38.921 − 288 =
39. 39.895 − 548 =
40. 40.222 − 148 =

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