Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 577 · 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. 1.704 − 278 =
2. 2.861 − 399 =
3. 3.884 − 799 =
4. 4.819 − 799 =
5. 5.746 − 199 =
6. 6.350 − 297 =
7. 7.889 − 607 =
8. 8.822 − 299 =
9. 9.784 − 497 =
10. 10.385 − 297 =
11. 11.709 − 169 =
12. 12.943 − 407 =
13. 13.675 − 299 =
14. 14.922 − 697 =
15. 15.374 − 198 =
16. 16.943 − 699 =
17. 17.786 − 297 =
18. 18.960 − 689 =
19. 19.513 − 369 =
20. 20.835 − 637 =
21. 21.995 − 798 =
22. 22.875 − 598 =
23. 23.340 − 249 =
24. 24.900 − 799 =
25. 25.859 − 599 =
26. 26.780 − 647 =
27. 27.239 − 198 =
28. 28.844 − 218 =
29. 29.772 − 699 =
30. 30.874 − 797 =
31. 31.780 − 169 =
32. 32.230 − 197 =
33. 33.921 − 498 =
34. 34.701 − 349 =
35. 35.479 − 298 =
36. 36.812 − 658 =
37. 37.743 − 518 =
38. 38.747 − 697 =
39. 39.611 − 299 =
40. 40.213 − 139 =

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