3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 485 · 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. 1.722 − 412 =
2. 2.488 + 127 =
3. 3.219 + 318 =
4. 4.638 − 246 =
5. 5.637 + 504 =
6. 6.512 + 614 =
7. 7.209 + 582 =
8. 8.419 + 216 =
9. 9.585 + 378 =
10. 10.885 − 314 =
11. 11.805 − 281 =
12. 12.419 − 222 =
13. 13.237 + 344 =
14. 14.530 + 158 =
15. 15.447 − 133 =
16. 16.986 − 393 =
17. 17.495 − 289 =
18. 18.667 − 441 =
19. 19.504 − 152 =
20. 20.180 + 281 =
21. 21.461 + 428 =
22. 22.629 + 152 =
23. 23.943 − 517 =
24. 24.554 − 396 =
25. 25.919 − 542 =
26. 26.257 + 409 =
27. 27.437 + 641 =
28. 28.950 − 222 =
29. 29.224 + 632 =
30. 30.728 − 603 =
31. 31.800 − 128 =
32. 32.390 + 465 =
33. 33.553 − 377 =
34. 34.624 + 629 =
35. 35.685 + 563 =
36. 36.761 + 121 =
37. 37.556 + 321 =
38. 38.607 − 392 =
39. 39.727 − 621 =
40. 40.517 − 367 =

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