3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 466 · 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. 1.227 + 351 =
2. 2.593 − 155 =
3. 3.609 − 442 =
4. 4.643 − 316 =
5. 5.648 − 413 =
6. 6.755 − 144 =
7. 7.260 + 411 =
8. 8.447 + 288 =
9. 9.302 + 589 =
10. 10.589 + 646 =
11. 11.526 − 356 =
12. 12.412 − 252 =
13. 13.433 − 124 =
14. 14.815 − 535 =
15. 15.937 − 197 =
16. 16.214 + 405 =
17. 17.259 + 546 =
18. 18.452 − 175 =
19. 19.596 + 397 =
20. 20.598 − 199 =
21. 21.412 − 244 =
22. 22.707 + 194 =
23. 23.598 + 584 =
24. 24.192 + 385 =
25. 25.451 + 597 =
26. 26.864 − 457 =
27. 27.788 − 631 =
28. 28.153 + 564 =
29. 29.688 − 351 =
30. 30.408 + 612 =
31. 31.457 − 336 =
32. 32.536 − 311 =
33. 33.201 + 517 =
34. 34.854 − 714 =
35. 35.836 − 117 =
36. 36.632 − 447 =
37. 37.603 − 141 =
38. 38.796 − 487 =
39. 39.565 − 361 =
40. 40.417 + 224 =

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