3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 39 · 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. 1.391 + 542 =
2. 2.428 − 131 =
3. 3.618 − 199 =
4. 4.373 + 409 =
5. 5.581 + 404 =
6. 6.906 − 364 =
7. 7.760 − 514 =
8. 8.573 − 141 =
9. 9.317 + 681 =
10. 10.791 − 661 =
11. 11.621 − 129 =
12. 12.936 − 655 =
13. 13.522 − 129 =
14. 14.335 + 607 =
15. 15.632 + 458 =
16. 16.667 + 489 =
17. 17.590 + 582 =
18. 18.476 − 295 =
19. 19.733 + 603 =
20. 20.243 + 468 =
21. 21.749 + 451 =
22. 22.421 − 121 =
23. 23.548 − 272 =
24. 24.783 + 435 =
25. 25.831 − 514 =
26. 26.475 + 271 =
27. 27.624 + 507 =
28. 28.606 − 235 =
29. 29.482 − 329 =
30. 30.572 + 141 =
31. 31.534 + 562 =
32. 32.748 − 238 =
33. 33.930 − 398 =
34. 34.681 − 299 =
35. 35.596 + 426 =
36. 36.821 − 278 =
37. 37.469 + 152 =
38. 38.188 + 367 =
39. 39.876 − 132 =
40. 40.603 + 184 =

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