Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 145 · 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. 1.826 − 448 =
2. 2.581 − 399 =
3. 3.477 − 399 =
4. 4.943 − 797 =
5. 5.965 − 368 =
6. 6.725 − 609 =
7. 7.984 − 598 =
8. 8.922 − 498 =
9. 9.680 − 599 =
10. 10.670 − 247 =
11. 11.575 − 197 =
12. 12.645 − 599 =
13. 13.553 − 119 =
14. 14.902 − 798 =
15. 15.769 − 377 =
16. 16.942 − 678 =
17. 17.706 − 199 =
18. 18.782 − 477 =
19. 19.744 − 219 =
20. 20.710 − 399 =
21. 21.752 − 139 =
22. 22.526 − 198 =
23. 23.446 − 268 =
24. 24.435 − 407 =
25. 25.707 − 637 =
26. 26.687 − 297 =
27. 27.590 − 397 =
28. 28.660 − 399 =
29. 29.706 − 439 =
30. 30.193 − 149 =
31. 31.600 − 497 =
32. 32.717 − 597 =
33. 33.338 − 199 =
34. 34.941 − 699 =
35. 35.730 − 438 =
36. 36.636 − 588 =
37. 37.811 − 538 =
38. 38.796 − 698 =
39. 39.673 − 589 =
40. 40.908 − 599 =

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