Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 494 · 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. 1.697 − 487 =
2. 2.841 − 119 =
3. 3.309 − 168 =
4. 4.622 − 397 =
5. 5.766 − 499 =
6. 6.730 − 617 =
7. 7.587 − 158 =
8. 8.227 − 198 =
9. 9.841 − 799 =
10. 10.942 − 427 =
11. 11.973 − 199 =
12. 12.740 − 599 =
13. 13.929 − 299 =
14. 14.746 − 198 =
15. 15.281 − 147 =
16. 16.641 − 598 =
17. 17.421 − 289 =
18. 18.926 − 698 =
19. 19.893 − 567 =
20. 20.284 − 197 =
21. 21.645 − 408 =
22. 22.827 − 198 =
23. 23.663 − 599 =
24. 24.231 − 197 =
25. 25.532 − 497 =
26. 26.452 − 147 =
27. 27.732 − 698 =
28. 28.874 − 238 =
29. 29.515 − 377 =
30. 30.570 − 197 =
31. 31.422 − 297 =
32. 32.688 − 598 =
33. 33.880 − 299 =
34. 34.949 − 317 =
35. 35.437 − 298 =
36. 36.925 − 239 =
37. 37.635 − 577 =
38. 38.706 − 249 =
39. 39.950 − 299 =
40. 40.636 − 598 =

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