Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 279 · 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. 1.473 − 419 =
2. 2.676 − 497 =
3. 3.456 − 219 =
4. 4.309 − 228 =
5. 5.884 − 619 =
6. 6.804 − 599 =
7. 7.755 − 398 =
8. 8.543 − 198 =
9. 9.823 − 548 =
10. 10.639 − 399 =
11. 11.814 − 419 =
12. 12.700 − 677 =
13. 13.511 − 399 =
14. 14.883 − 658 =
15. 15.469 − 299 =
16. 16.972 − 639 =
17. 17.556 − 418 =
18. 18.879 − 799 =
19. 19.300 − 147 =
20. 20.935 − 198 =
21. 21.772 − 399 =
22. 22.436 − 399 =
23. 23.828 − 798 =
24. 24.612 − 299 =
25. 25.634 − 537 =
26. 26.748 − 497 =
27. 27.840 − 798 =
28. 28.627 − 497 =
29. 29.420 − 199 =
30. 30.934 − 638 =
31. 31.993 − 797 =
32. 32.931 − 297 =
33. 33.592 − 509 =
34. 34.849 − 699 =
35. 35.692 − 567 =
36. 36.925 − 598 =
37. 37.636 − 568 =
38. 38.848 − 497 =
39. 39.909 − 497 =
40. 40.837 − 799 =

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