3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 828 · 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. 1.130 + 404 =
2. 2.460 − 356 =
3. 3.676 − 127 =
4. 4.788 − 209 =
5. 5.648 + 605 =
6. 6.538 − 359 =
7. 7.143 + 271 =
8. 8.525 − 193 =
9. 9.735 + 302 =
10. 10.290 + 528 =
11. 11.970 − 531 =
12. 12.171 + 574 =
13. 13.802 − 411 =
14. 14.164 + 451 =
15. 15.418 − 213 =
16. 16.888 − 384 =
17. 17.794 − 312 =
18. 18.748 + 685 =
19. 19.976 − 537 =
20. 20.531 − 414 =
21. 21.344 + 125 =
22. 22.565 − 375 =
23. 23.839 − 387 =
24. 24.833 − 313 =
25. 25.647 − 125 =
26. 26.833 − 706 =
27. 27.758 − 461 =
28. 28.629 − 173 =
29. 29.840 − 496 =
30. 30.621 + 117 =
31. 31.577 + 543 =
32. 32.822 − 547 =
33. 33.472 − 136 =
34. 34.904 − 761 =
35. 35.316 + 181 =
36. 36.721 − 114 =
37. 37.241 + 273 =
38. 38.252 + 684 =
39. 39.522 − 303 =
40. 40.214 + 214 =

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