Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 671 · 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. 1.726 − 408 =
2. 2.790 − 398 =
3. 3.741 − 487 =
4. 4.705 − 527 =
5. 5.795 − 257 =
6. 6.831 − 537 =
7. 7.680 − 149 =
8. 8.672 − 598 =
9. 9.925 − 518 =
10. 10.819 − 207 =
11. 11.611 − 118 =
12. 12.371 − 298 =
13. 13.867 − 497 =
14. 14.845 − 379 =
15. 15.883 − 799 =
16. 16.698 − 499 =
17. 17.731 − 399 =
18. 18.715 − 639 =
19. 19.568 − 427 =
20. 20.698 − 397 =
21. 21.953 − 547 =
22. 22.791 − 617 =
23. 23.445 − 407 =
24. 24.908 − 599 =
25. 25.498 − 219 =
26. 26.874 − 399 =
27. 27.590 − 197 =
28. 28.234 − 199 =
29. 29.196 − 168 =
30. 30.951 − 797 =
31. 31.860 − 798 =
32. 32.958 − 699 =
33. 33.996 − 699 =
34. 34.734 − 599 =
35. 35.926 − 658 =
36. 36.767 − 697 =
37. 37.758 − 599 =
38. 38.512 − 477 =
39. 39.740 − 468 =
40. 40.886 − 698 =

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