Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 63 · 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. 1.730 − 697 =
2. 2.535 − 397 =
3. 3.592 − 538 =
4. 4.610 − 298 =
5. 5.449 − 398 =
6. 6.409 − 208 =
7. 7.515 − 198 =
8. 8.456 − 297 =
9. 9.938 − 199 =
10. 10.931 − 427 =
11. 11.782 − 619 =
12. 12.705 − 347 =
13. 13.829 − 309 =
14. 14.977 − 799 =
15. 15.888 − 498 =
16. 16.815 − 309 =
17. 17.716 − 529 =
18. 18.811 − 699 =
19. 19.310 − 199 =
20. 20.462 − 398 =
21. 21.960 − 698 =
22. 22.758 − 367 =
23. 23.281 − 128 =
24. 24.988 − 399 =
25. 25.612 − 148 =
26. 26.917 − 628 =
27. 27.955 − 278 =
28. 28.992 − 299 =
29. 29.624 − 598 =
30. 30.854 − 699 =
31. 31.856 − 297 =
32. 32.789 − 177 =
33. 33.365 − 237 =
34. 34.720 − 699 =
35. 35.823 − 397 =
36. 36.815 − 319 =
37. 37.605 − 498 =
38. 38.836 − 598 =
39. 39.376 − 198 =
40. 40.389 − 298 =

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