3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 110 · 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. 1.638 + 419 =
2. 2.418 + 479 =
3. 3.756 − 457 =
4. 4.633 + 254 =
5. 5.484 − 171 =
6. 6.642 − 313 =
7. 7.894 − 162 =
8. 8.460 − 298 =
9. 9.763 − 659 =
10. 10.311 + 522 =
11. 11.597 + 412 =
12. 12.275 + 511 =
13. 13.836 − 179 =
14. 14.450 − 277 =
15. 15.432 + 513 =
16. 16.604 + 689 =
17. 17.462 − 292 =
18. 18.914 − 151 =
19. 19.534 + 161 =
20. 20.149 + 525 =
21. 21.627 + 627 =
22. 22.540 − 309 =
23. 23.563 − 169 =
24. 24.435 − 258 =
25. 25.310 + 601 =
26. 26.320 + 135 =
27. 27.603 − 411 =
28. 28.930 − 152 =
29. 29.399 + 431 =
30. 30.887 − 755 =
31. 31.713 − 521 =
32. 32.496 + 112 =
33. 33.737 − 206 =
34. 34.812 − 449 =
35. 35.687 − 301 =
36. 36.635 − 209 =
37. 37.453 − 315 =
38. 38.832 − 699 =
39. 39.859 − 442 =
40. 40.435 + 291 =

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