3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 628 · 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. 1.623 − 236 =
2. 2.582 − 471 =
3. 3.719 − 387 =
4. 4.478 + 557 =
5. 5.645 + 509 =
6. 6.301 + 544 =
7. 7.333 + 551 =
8. 8.570 + 242 =
9. 9.366 + 329 =
10. 10.635 − 408 =
11. 11.980 − 345 =
12. 12.554 + 401 =
13. 13.546 + 343 =
14. 14.307 + 436 =
15. 15.392 + 616 =
16. 16.840 − 403 =
17. 17.703 + 155 =
18. 18.778 − 348 =
19. 19.760 − 528 =
20. 20.421 − 151 =
21. 21.604 − 191 =
22. 22.825 − 572 =
23. 23.300 + 374 =
24. 24.571 − 278 =
25. 25.571 − 324 =
26. 26.559 + 277 =
27. 27.653 − 326 =
28. 28.209 + 441 =
29. 29.169 + 431 =
30. 30.132 + 341 =
31. 31.714 + 274 =
32. 32.311 + 589 =
33. 33.665 − 355 =
34. 34.531 − 353 =
35. 35.291 + 542 =
36. 36.488 − 241 =
37. 37.443 − 131 =
38. 38.825 − 391 =
39. 39.582 − 379 =
40. 40.767 + 575 =

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