Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 69 · 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. 1.736 − 298 =
2. 2.762 − 507 =
3. 3.784 − 258 =
4. 4.626 − 388 =
5. 5.583 − 198 =
6. 6.908 − 298 =
7. 7.695 − 299 =
8. 8.825 − 157 =
9. 9.852 − 798 =
10. 10.691 − 577 =
11. 11.615 − 138 =
12. 12.832 − 398 =
13. 13.686 − 598 =
14. 14.659 − 297 =
15. 15.923 − 799 =
16. 16.806 − 508 =
17. 17.884 − 578 =
18. 18.404 − 219 =
19. 19.941 − 599 =
20. 20.727 − 158 =
21. 21.931 − 518 =
22. 22.855 − 478 =
23. 23.984 − 399 =
24. 24.829 − 797 =
25. 25.436 − 199 =
26. 26.751 − 597 =
27. 27.897 − 599 =
28. 28.468 − 198 =
29. 29.520 − 299 =
30. 30.902 − 698 =
31. 31.630 − 529 =
32. 32.551 − 227 =
33. 33.636 − 438 =
34. 34.752 − 187 =
35. 35.934 − 587 =
36. 36.978 − 639 =
37. 37.684 − 259 =
38. 38.781 − 279 =
39. 39.977 − 608 =
40. 40.644 − 188 =

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