Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 478 · 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. 1.860 − 799 =
2. 2.936 − 197 =
3. 3.578 − 489 =
4. 4.954 − 597 =
5. 5.933 − 619 =
6. 6.886 − 298 =
7. 7.891 − 198 =
8. 8.822 − 398 =
9. 9.824 − 698 =
10. 10.407 − 198 =
11. 11.452 − 318 =
12. 12.454 − 367 =
13. 13.722 − 398 =
14. 14.972 − 598 =
15. 15.735 − 599 =
16. 16.999 − 597 =
17. 17.671 − 208 =
18. 18.635 − 197 =
19. 19.445 − 119 =
20. 20.787 − 297 =
21. 21.837 − 599 =
22. 22.506 − 479 =
23. 23.548 − 187 =
24. 24.715 − 527 =
25. 25.501 − 399 =
26. 26.324 − 197 =
27. 27.837 − 347 =
28. 28.978 − 369 =
29. 29.689 − 659 =
30. 30.819 − 497 =
31. 31.590 − 197 =
32. 32.306 − 197 =
33. 33.853 − 797 =
34. 34.815 − 397 =
35. 35.839 − 699 =
36. 36.898 − 798 =
37. 37.446 − 198 =
38. 38.850 − 798 =
39. 39.351 − 148 =
40. 40.792 − 659 =

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