Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 24 · 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. 1.636 − 499 =
2. 2.742 − 497 =
3. 3.470 − 167 =
4. 4.619 − 469 =
5. 5.826 − 798 =
6. 6.669 − 297 =
7. 7.723 − 378 =
8. 8.875 − 799 =
9. 9.921 − 577 =
10. 10.724 − 217 =
11. 11.719 − 599 =
12. 12.820 − 549 =
13. 13.820 − 797 =
14. 14.488 − 299 =
15. 15.895 − 528 =
16. 16.850 − 229 =
17. 17.697 − 567 =
18. 18.835 − 799 =
19. 19.705 − 187 =
20. 20.968 − 498 =
21. 21.777 − 607 =
22. 22.781 − 569 =
23. 23.855 − 797 =
24. 24.947 − 399 =
25. 25.697 − 258 =
26. 26.387 − 228 =
27. 27.783 − 499 =
28. 28.536 − 399 =
29. 29.727 − 607 =
30. 30.674 − 587 =
31. 31.796 − 697 =
32. 32.752 − 449 =
33. 33.937 − 639 =
34. 34.813 − 499 =
35. 35.789 − 699 =
36. 36.996 − 698 =
37. 37.876 − 389 =
38. 38.974 − 199 =
39. 39.402 − 169 =
40. 40.852 − 229 =

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