3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 462 · 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. 1.729 + 353 =
2. 2.768 − 276 =
3. 3.167 + 284 =
4. 4.469 + 603 =
5. 5.260 + 688 =
6. 6.566 + 641 =
7. 7.380 + 264 =
8. 8.760 − 392 =
9. 9.656 − 409 =
10. 10.490 − 268 =
11. 11.141 + 257 =
12. 12.454 + 181 =
13. 13.593 + 287 =
14. 14.478 + 225 =
15. 15.507 − 211 =
16. 16.346 + 241 =
17. 17.730 + 181 =
18. 18.813 − 238 =
19. 19.554 − 439 =
20. 20.685 − 265 =
21. 21.413 − 172 =
22. 22.702 + 247 =
23. 23.446 + 326 =
24. 24.604 − 342 =
25. 25.697 − 227 =
26. 26.649 − 356 =
27. 27.414 − 116 =
28. 28.491 + 653 =
29. 29.659 + 143 =
30. 30.647 − 117 =
31. 31.869 − 536 =
32. 32.720 + 574 =
33. 33.499 + 298 =
34. 34.339 + 379 =
35. 35.700 + 342 =
36. 36.667 − 168 =
37. 37.548 − 312 =
38. 38.904 − 679 =
39. 39.422 − 123 =
40. 40.521 + 446 =

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