Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 105 · 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. 1.837 − 699 =
2. 2.844 − 298 =
3. 3.586 − 419 =
4. 4.838 − 597 =
5. 5.911 − 599 =
6. 6.779 − 499 =
7. 7.966 − 619 =
8. 8.846 − 298 =
9. 9.290 − 217 =
10. 10.658 − 557 =
11. 11.441 − 139 =
12. 12.332 − 198 =
13. 13.542 − 438 =
14. 14.784 − 499 =
15. 15.931 − 699 =
16. 16.609 − 498 =
17. 17.816 − 698 =
18. 18.871 − 399 =
19. 19.827 − 539 =
20. 20.669 − 119 =
21. 21.858 − 599 =
22. 22.947 − 498 =
23. 23.900 − 138 =
24. 24.697 − 499 =
25. 25.792 − 627 =
26. 26.754 − 698 =
27. 27.613 − 547 =
28. 28.526 − 508 =
29. 29.917 − 577 =
30. 30.678 − 497 =
31. 31.658 − 548 =
32. 32.484 − 439 =
33. 33.934 − 799 =
34. 34.787 − 408 =
35. 35.820 − 497 =
36. 36.675 − 499 =
37. 37.744 − 597 =
38. 38.367 − 198 =
39. 39.967 − 797 =
40. 40.694 − 668 =

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