Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 972 · 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. 1.774 − 519 =
2. 2.854 − 597 =
3. 3.593 − 198 =
4. 4.959 − 799 =
5. 5.448 − 298 =
6. 6.978 − 318 =
7. 7.755 − 299 =
8. 8.470 − 299 =
9. 9.731 − 398 =
10. 10.675 − 439 =
11. 11.831 − 628 =
12. 12.652 − 398 =
13. 13.974 − 578 =
14. 14.601 − 497 =
15. 15.692 − 497 =
16. 16.713 − 399 =
17. 17.761 − 459 =
18. 18.389 − 298 =
19. 19.426 − 398 =
20. 20.924 − 367 =
21. 21.968 − 799 =
22. 22.768 − 177 =
23. 23.874 − 297 =
24. 24.630 − 127 =
25. 25.907 − 398 =
26. 26.900 − 399 =
27. 27.806 − 499 =
28. 28.593 − 509 =
29. 29.966 − 697 =
30. 30.968 − 599 =
31. 31.897 − 399 =
32. 32.466 − 359 =
33. 33.610 − 399 =
34. 34.984 − 477 =
35. 35.812 − 697 =
36. 36.597 − 417 =
37. 37.948 − 199 =
38. 38.683 − 579 =
39. 39.732 − 397 =
40. 40.603 − 399 =

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