3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 778 · 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. 1.561 − 404 =
2. 2.568 − 283 =
3. 3.804 − 541 =
4. 4.259 + 586 =
5. 5.536 + 441 =
6. 6.300 + 421 =
7. 7.694 + 401 =
8. 8.561 + 678 =
9. 9.678 − 349 =
10. 10.746 − 347 =
11. 11.606 − 317 =
12. 12.458 + 168 =
13. 13.572 + 368 =
14. 14.823 − 414 =
15. 15.464 − 178 =
16. 16.455 − 291 =
17. 17.545 − 286 =
18. 18.723 − 241 =
19. 19.654 + 336 =
20. 20.745 + 523 =
21. 21.525 − 284 =
22. 22.462 − 151 =
23. 23.177 + 382 =
24. 24.599 − 473 =
25. 25.738 + 218 =
26. 26.899 − 567 =
27. 27.517 + 445 =
28. 28.639 + 112 =
29. 29.886 − 271 =
30. 30.750 + 281 =
31. 31.193 + 251 =
32. 32.652 + 444 =
33. 33.915 − 482 =
34. 34.578 − 364 =
35. 35.733 − 239 =
36. 36.420 + 337 =
37. 37.619 − 205 =
38. 38.128 + 227 =
39. 39.581 − 479 =
40. 40.149 + 445 =

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