Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 533 · 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. 1.346 − 198 =
2. 2.879 − 378 =
3. 3.682 − 198 =
4. 4.293 − 197 =
5. 5.761 − 697 =
6. 6.804 − 599 =
7. 7.933 − 698 =
8. 8.942 − 679 =
9. 9.784 − 399 =
10. 10.937 − 617 =
11. 11.962 − 497 =
12. 12.534 − 298 =
13. 13.899 − 799 =
14. 14.913 − 519 =
15. 15.718 − 298 =
16. 16.755 − 139 =
17. 17.386 − 268 =
18. 18.490 − 159 =
19. 19.785 − 389 =
20. 20.820 − 397 =
21. 21.699 − 237 =
22. 22.668 − 299 =
23. 23.842 − 799 =
24. 24.448 − 268 =
25. 25.970 − 798 =
26. 26.630 − 549 =
27. 27.764 − 297 =
28. 28.764 − 487 =
29. 29.504 − 297 =
30. 30.759 − 128 =
31. 31.901 − 629 =
32. 32.839 − 469 =
33. 33.786 − 427 =
34. 34.634 − 199 =
35. 35.804 − 698 =
36. 36.834 − 588 =
37. 37.749 − 698 =
38. 38.461 − 399 =
39. 39.234 − 199 =
40. 40.847 − 198 =

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