Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 679 · 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. 1.710 − 427 =
2. 2.905 − 697 =
3. 3.908 − 698 =
4. 4.695 − 199 =
5. 5.604 − 317 =
6. 6.822 − 698 =
7. 7.451 − 297 =
8. 8.236 − 148 =
9. 9.589 − 497 =
10. 10.705 − 198 =
11. 11.574 − 399 =
12. 12.805 − 448 =
13. 13.997 − 299 =
14. 14.767 − 567 =
15. 15.455 − 197 =
16. 16.956 − 399 =
17. 17.970 − 447 =
18. 18.965 − 208 =
19. 19.635 − 347 =
20. 20.837 − 497 =
21. 21.890 − 127 =
22. 22.673 − 597 =
23. 23.933 − 678 =
24. 24.569 − 497 =
25. 25.233 − 119 =
26. 26.613 − 569 =
27. 27.819 − 497 =
28. 28.993 − 799 =
29. 29.871 − 599 =
30. 30.685 − 199 =
31. 31.925 − 798 =
32. 32.813 − 798 =
33. 33.755 − 619 =
34. 34.675 − 649 =
35. 35.624 − 599 =
36. 36.843 − 398 =
37. 37.988 − 617 =
38. 38.635 − 298 =
39. 39.746 − 699 =
40. 40.438 − 298 =

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