Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 923 · 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. 1.901 − 398 =
2. 2.874 − 298 =
3. 3.735 − 397 =
4. 4.784 − 197 =
5. 5.600 − 377 =
6. 6.472 − 299 =
7. 7.333 − 219 =
8. 8.991 − 609 =
9. 9.472 − 199 =
10. 10.923 − 608 =
11. 11.648 − 249 =
12. 12.826 − 798 =
13. 13.966 − 158 =
14. 14.826 − 208 =
15. 15.572 − 399 =
16. 16.641 − 219 =
17. 17.812 − 658 =
18. 18.719 − 407 =
19. 19.353 − 197 =
20. 20.727 − 299 =
21. 21.833 − 699 =
22. 22.954 − 499 =
23. 23.775 − 209 =
24. 24.860 − 499 =
25. 25.780 − 278 =
26. 26.670 − 518 =
27. 27.430 − 398 =
28. 28.678 − 328 =
29. 29.949 − 668 =
30. 30.543 − 498 =
31. 31.590 − 397 =
32. 32.891 − 629 =
33. 33.711 − 598 =
34. 34.649 − 277 =
35. 35.600 − 169 =
36. 36.779 − 698 =
37. 37.915 − 119 =
38. 38.653 − 199 =
39. 39.679 − 497 =
40. 40.955 − 697 =

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