Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 788 · 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. 1.497 − 297 =
2. 2.881 − 297 =
3. 3.703 − 598 =
4. 4.948 − 507 =
5. 5.917 − 797 =
6. 6.541 − 398 =
7. 7.851 − 399 =
8. 8.259 − 198 =
9. 9.785 − 498 =
10. 10.987 − 319 =
11. 11.888 − 598 =
12. 12.713 − 697 =
13. 13.957 − 429 =
14. 14.720 − 549 =
15. 15.819 − 447 =
16. 16.655 − 328 =
17. 17.588 − 498 =
18. 18.533 − 498 =
19. 19.807 − 689 =
20. 20.990 − 177 =
21. 21.570 − 357 =
22. 22.977 − 397 =
23. 23.743 − 198 =
24. 24.920 − 598 =
25. 25.590 − 398 =
26. 26.860 − 697 =
27. 27.779 − 699 =
28. 28.805 − 598 =
29. 29.609 − 588 =
30. 30.822 − 798 =
31. 31.201 − 127 =
32. 32.501 − 317 =
33. 33.993 − 399 =
34. 34.955 − 399 =
35. 35.818 − 398 =
36. 36.817 − 799 =
37. 37.553 − 397 =
38. 38.969 − 309 =
39. 39.676 − 198 =
40. 40.377 − 198 =

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