Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 619 · 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. 1.311 − 208 =
2. 2.521 − 197 =
3. 3.234 − 198 =
4. 4.933 − 497 =
5. 5.733 − 199 =
6. 6.275 − 127 =
7. 7.555 − 399 =
8. 8.875 − 119 =
9. 9.738 − 597 =
10. 10.927 − 499 =
11. 11.908 − 798 =
12. 12.942 − 498 =
13. 13.879 − 239 =
14. 14.537 − 517 =
15. 15.894 − 197 =
16. 16.942 − 648 =
17. 17.669 − 439 =
18. 18.582 − 228 =
19. 19.474 − 138 =
20. 20.255 − 119 =
21. 21.875 − 218 =
22. 22.701 − 589 =
23. 23.725 − 289 =
24. 24.703 − 578 =
25. 25.869 − 529 =
26. 26.847 − 609 =
27. 27.726 − 538 =
28. 28.699 − 577 =
29. 29.837 − 799 =
30. 30.926 − 217 =
31. 31.792 − 699 =
32. 32.982 − 137 =
33. 33.305 − 117 =
34. 34.956 − 797 =
35. 35.896 − 399 =
36. 36.599 − 497 =
37. 37.807 − 268 =
38. 38.783 − 499 =
39. 39.766 − 659 =
40. 40.771 − 397 =

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