Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 728 · 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. 1.974 − 668 =
2. 2.813 − 198 =
3. 3.299 − 197 =
4. 4.767 − 498 =
5. 5.986 − 298 =
6. 6.868 − 799 =
7. 7.506 − 297 =
8. 8.271 − 199 =
9. 9.990 − 378 =
10. 10.422 − 298 =
11. 11.961 − 498 =
12. 12.883 − 127 =
13. 13.798 − 598 =
14. 14.857 − 399 =
15. 15.370 − 318 =
16. 16.781 − 297 =
17. 17.820 − 659 =
18. 18.712 − 499 =
19. 19.582 − 199 =
20. 20.518 − 299 =
21. 21.881 − 697 =
22. 22.536 − 199 =
23. 23.655 − 319 =
24. 24.822 − 197 =
25. 25.660 − 297 =
26. 26.770 − 549 =
27. 27.896 − 797 =
28. 28.753 − 498 =
29. 29.973 − 799 =
30. 30.532 − 409 =
31. 31.448 − 149 =
32. 32.988 − 697 =
33. 33.918 − 287 =
34. 34.726 − 398 =
35. 35.805 − 277 =
36. 36.966 − 497 =
37. 37.989 − 497 =
38. 38.760 − 609 =
39. 39.192 − 117 =
40. 40.282 − 199 =

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