Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 540 · 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. 1.545 − 149 =
2. 2.727 − 208 =
3. 3.868 − 309 =
4. 4.999 − 598 =
5. 5.637 − 497 =
6. 6.291 − 169 =
7. 7.939 − 397 =
8. 8.601 − 427 =
9. 9.892 − 599 =
10. 10.711 − 198 =
11. 11.885 − 528 =
12. 12.960 − 399 =
13. 13.716 − 699 =
14. 14.982 − 499 =
15. 15.975 − 677 =
16. 16.802 − 299 =
17. 17.736 − 307 =
18. 18.728 − 449 =
19. 19.486 − 448 =
20. 20.412 − 347 =
21. 21.755 − 358 =
22. 22.891 − 699 =
23. 23.820 − 397 =
24. 24.243 − 199 =
25. 25.983 − 797 =
26. 26.975 − 497 =
27. 27.760 − 598 =
28. 28.724 − 499 =
29. 29.973 − 699 =
30. 30.582 − 498 =
31. 31.637 − 518 =
32. 32.698 − 499 =
33. 33.447 − 369 =
34. 34.817 − 598 =
35. 35.929 − 698 =
36. 36.743 − 198 =
37. 37.815 − 679 =
38. 38.457 − 398 =
39. 39.928 − 697 =
40. 40.857 − 798 =

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