3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 544 · 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. 1.224 + 172 =
2. 2.735 + 542 =
3. 3.274 + 508 =
4. 4.594 + 371 =
5. 5.469 − 112 =
6. 6.620 + 389 =
7. 7.237 + 598 =
8. 8.524 + 516 =
9. 9.418 + 429 =
10. 10.555 − 118 =
11. 11.447 + 638 =
12. 12.433 + 351 =
13. 13.388 + 141 =
14. 14.457 − 193 =
15. 15.441 − 332 =
16. 16.455 − 118 =
17. 17.784 + 382 =
18. 18.580 − 334 =
19. 19.498 − 372 =
20. 20.930 − 305 =
21. 21.313 + 188 =
22. 22.779 − 614 =
23. 23.713 + 644 =
24. 24.294 + 131 =
25. 25.581 − 209 =
26. 26.560 − 123 =
27. 27.598 + 287 =
28. 28.333 + 511 =
29. 29.336 + 324 =
30. 30.500 − 123 =
31. 31.773 − 114 =
32. 32.710 − 477 =
33. 33.595 − 393 =
34. 34.568 − 355 =
35. 35.640 − 368 =
36. 36.530 − 183 =
37. 37.443 − 323 =
38. 38.606 − 397 =
39. 39.260 + 167 =
40. 40.766 + 468 =

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