Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 555 · 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. 1.586 − 347 =
2. 2.736 − 117 =
3. 3.900 − 798 =
4. 4.925 − 217 =
5. 5.902 − 799 =
6. 6.939 − 298 =
7. 7.743 − 699 =
8. 8.872 − 399 =
9. 9.515 − 398 =
10. 10.991 − 198 =
11. 11.818 − 559 =
12. 12.995 − 799 =
13. 13.795 − 297 =
14. 14.536 − 147 =
15. 15.842 − 398 =
16. 16.736 − 498 =
17. 17.391 − 197 =
18. 18.445 − 408 =
19. 19.476 − 347 =
20. 20.950 − 477 =
21. 21.447 − 199 =
22. 22.891 − 797 =
23. 23.318 − 228 =
24. 24.856 − 698 =
25. 25.660 − 499 =
26. 26.488 − 399 =
27. 27.998 − 578 =
28. 28.914 − 598 =
29. 29.816 − 579 =
30. 30.678 − 599 =
31. 31.784 − 698 =
32. 32.807 − 597 =
33. 33.996 − 629 =
34. 34.861 − 699 =
35. 35.685 − 599 =
36. 36.658 − 198 =
37. 37.668 − 587 =
38. 38.398 − 307 =
39. 39.926 − 507 =
40. 40.865 − 669 =

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