3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 645 · 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. 1.620 + 625 =
2. 2.928 − 662 =
3. 3.540 + 222 =
4. 4.180 + 271 =
5. 5.573 − 293 =
6. 6.646 + 512 =
7. 7.333 + 141 =
8. 8.435 + 409 =
9. 9.506 + 341 =
10. 10.618 + 238 =
11. 11.216 + 221 =
12. 12.638 + 357 =
13. 13.790 − 564 =
14. 14.275 + 383 =
15. 15.341 + 202 =
16. 16.530 + 538 =
17. 17.783 + 129 =
18. 18.772 + 485 =
19. 19.534 − 201 =
20. 20.728 + 629 =
21. 21.590 + 148 =
22. 22.764 − 588 =
23. 23.566 − 462 =
24. 24.722 − 161 =
25. 25.589 + 361 =
26. 26.845 − 291 =
27. 27.830 − 393 =
28. 28.322 + 346 =
29. 29.782 − 295 =
30. 30.541 − 194 =
31. 31.876 − 141 =
32. 32.366 + 181 =
33. 33.738 − 436 =
34. 34.131 + 323 =
35. 35.584 + 537 =
36. 36.681 − 138 =
37. 37.144 + 607 =
38. 38.523 − 306 =
39. 39.567 − 125 =
40. 40.523 − 314 =

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