3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 300 · 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. 1.191 + 332 =
2. 2.698 + 133 =
3. 3.268 + 284 =
4. 4.713 + 459 =
5. 5.485 − 137 =
6. 6.648 + 449 =
7. 7.846 − 498 =
8. 8.583 − 294 =
9. 9.424 + 389 =
10. 10.561 + 524 =
11. 11.735 − 222 =
12. 12.538 − 401 =
13. 13.376 + 201 =
14. 14.904 − 646 =
15. 15.546 + 242 =
16. 16.372 + 431 =
17. 17.690 − 304 =
18. 18.200 + 564 =
19. 19.839 − 687 =
20. 20.755 − 138 =
21. 21.883 − 159 =
22. 22.300 + 454 =
23. 23.412 + 466 =
24. 24.227 + 527 =
25. 25.497 − 281 =
26. 26.761 − 353 =
27. 27.553 − 316 =
28. 28.713 − 175 =
29. 29.374 + 488 =
30. 30.628 + 427 =
31. 31.567 + 511 =
32. 32.420 − 311 =
33. 33.969 − 318 =
34. 34.639 − 243 =
35. 35.504 + 636 =
36. 36.246 + 171 =
37. 37.963 − 725 =
38. 38.590 − 141 =
39. 39.238 + 133 =
40. 40.560 − 123 =

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