3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 861 · 40 questions

How to do it in your head (Hundreds first): Keep the first number as it is and split the second into hundreds, tens and ones. Add (or take away) the hundreds first, then the tens. Finish with the ones — bridge through a ten if you need to.

1. 1.805 − 686 =
2. 2.741 − 453 =
3. 3.739 − 354 =
4. 4.877 − 585 =
5. 5.888 − 117 =
6. 6.639 − 387 =
7. 7.445 + 661 =
8. 8.619 + 576 =
9. 9.434 + 305 =
10. 10.656 − 542 =
11. 11.823 − 561 =
12. 12.606 − 258 =
13. 13.722 − 177 =
14. 14.873 − 184 =
15. 15.203 + 467 =
16. 16.584 − 318 =
17. 17.841 − 315 =
18. 18.563 + 154 =
19. 19.680 − 186 =
20. 20.890 − 221 =
21. 21.200 + 621 =
22. 22.927 − 437 =
23. 23.548 + 661 =
24. 24.334 + 441 =
25. 25.778 + 577 =
26. 26.414 − 113 =
27. 27.766 − 132 =
28. 28.871 − 589 =
29. 29.462 − 131 =
30. 30.574 + 319 =
31. 31.643 + 267 =
32. 32.444 + 215 =
33. 33.769 − 159 =
34. 34.167 + 609 =
35. 35.243 + 112 =
36. 36.425 − 132 =
37. 37.587 − 415 =
38. 38.857 − 642 =
39. 39.383 + 409 =
40. 40.609 − 218 =

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