Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 231 · 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. 1.879 − 639 =
2. 2.364 − 269 =
3. 3.729 − 697 =
4. 4.776 − 298 =
5. 5.359 − 317 =
6. 6.419 − 147 =
7. 7.930 − 297 =
8. 8.864 − 799 =
9. 9.251 − 199 =
10. 10.599 − 487 =
11. 11.389 − 268 =
12. 12.555 − 377 =
13. 13.645 − 597 =
14. 14.869 − 798 =
15. 15.463 − 219 =
16. 16.827 − 699 =
17. 17.941 − 697 =
18. 18.609 − 499 =
19. 19.709 − 399 =
20. 20.864 − 159 =
21. 21.916 − 619 =
22. 22.770 − 447 =
23. 23.644 − 309 =
24. 24.577 − 399 =
25. 25.584 − 279 =
26. 26.755 − 558 =
27. 27.827 − 609 =
28. 28.375 − 298 =
29. 29.789 − 698 =
30. 30.779 − 578 =
31. 31.938 − 599 =
32. 32.930 − 798 =
33. 33.400 − 207 =
34. 34.962 − 597 =
35. 35.515 − 297 =
36. 36.757 − 379 =
37. 37.610 − 528 =
38. 38.827 − 797 =
39. 39.952 − 398 =
40. 40.916 − 799 =

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