3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 914 · 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. 1.329 + 553 =
2. 2.840 − 579 =
3. 3.568 − 135 =
4. 4.831 − 123 =
5. 5.714 + 557 =
6. 6.655 − 419 =
7. 7.650 − 437 =
8. 8.425 − 114 =
9. 9.404 + 521 =
10. 10.429 + 498 =
11. 11.791 − 691 =
12. 12.590 + 405 =
13. 13.509 − 341 =
14. 14.758 − 631 =
15. 15.450 − 209 =
16. 16.471 + 272 =
17. 17.627 − 116 =
18. 18.420 − 256 =
19. 19.497 + 679 =
20. 20.593 + 371 =
21. 21.471 + 568 =
22. 22.779 − 295 =
23. 23.423 + 176 =
24. 24.415 + 306 =
25. 25.568 − 144 =
26. 26.903 − 421 =
27. 27.934 − 804 =
28. 28.692 − 223 =
29. 29.411 + 457 =
30. 30.875 − 309 =
31. 31.425 − 214 =
32. 32.150 + 253 =
33. 33.732 − 551 =
34. 34.703 − 558 =
35. 35.607 + 237 =
36. 36.813 − 675 =
37. 37.357 + 315 =
38. 38.975 − 214 =
39. 39.940 − 348 =
40. 40.702 − 325 =

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