Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 465 · 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. 1.688 − 399 =
2. 2.755 − 199 =
3. 3.655 − 399 =
4. 4.906 − 797 =
5. 5.959 − 597 =
6. 6.810 − 697 =
7. 7.883 − 799 =
8. 8.748 − 197 =
9. 9.887 − 679 =
10. 10.323 − 118 =
11. 11.640 − 528 =
12. 12.676 − 647 =
13. 13.613 − 397 =
14. 14.486 − 407 =
15. 15.885 − 197 =
16. 16.905 − 797 =
17. 17.695 − 399 =
18. 18.795 − 399 =
19. 19.692 − 657 =
20. 20.628 − 397 =
21. 21.999 − 697 =
22. 22.991 − 198 =
23. 23.775 − 497 =
24. 24.925 − 699 =
25. 25.697 − 137 =
26. 26.634 − 357 =
27. 27.547 − 199 =
28. 28.819 − 798 =
29. 29.957 − 199 =
30. 30.982 − 449 =
31. 31.718 − 698 =
32. 32.560 − 198 =
33. 33.424 − 219 =
34. 34.947 − 199 =
35. 35.594 − 497 =
36. 36.568 − 397 =
37. 37.654 − 429 =
38. 38.768 − 337 =
39. 39.933 − 339 =
40. 40.664 − 248 =

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