Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 56 · 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. 1.639 − 387 =
2. 2.317 − 159 =
3. 3.911 − 698 =
4. 4.742 − 697 =
5. 5.843 − 499 =
6. 6.941 − 428 =
7. 7.966 − 439 =
8. 8.960 − 697 =
9. 9.351 − 129 =
10. 10.699 − 359 =
11. 11.952 − 509 =
12. 12.473 − 399 =
13. 13.570 − 398 =
14. 14.738 − 598 =
15. 15.481 − 278 =
16. 16.560 − 299 =
17. 17.651 − 297 =
18. 18.837 − 798 =
19. 19.648 − 597 =
20. 20.641 − 168 =
21. 21.416 − 298 =
22. 22.848 − 368 =
23. 23.726 − 698 =
24. 24.560 − 127 =
25. 25.307 − 229 =
26. 26.381 − 348 =
27. 27.809 − 598 =
28. 28.412 − 399 =
29. 29.246 − 139 =
30. 30.509 − 399 =
31. 31.793 − 417 =
32. 32.930 − 798 =
33. 33.489 − 399 =
34. 34.750 − 617 =
35. 35.889 − 598 =
36. 36.395 − 297 =
37. 37.761 − 369 =
38. 38.743 − 587 =
39. 39.633 − 609 =
40. 40.884 − 599 =

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