3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 478 · 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. 1.972 − 145 =
2. 2.595 − 203 =
3. 3.196 + 164 =
4. 4.607 − 232 =
5. 5.205 + 311 =
6. 6.556 − 142 =
7. 7.732 + 249 =
8. 8.599 + 434 =
9. 9.468 − 142 =
10. 10.428 + 255 =
11. 11.958 − 771 =
12. 12.369 + 641 =
13. 13.968 − 561 =
14. 14.460 + 596 =
15. 15.448 − 263 =
16. 16.639 − 533 =
17. 17.535 − 328 =
18. 18.341 + 311 =
19. 19.144 + 544 =
20. 20.740 − 181 =
21. 21.926 − 756 =
22. 22.695 − 486 =
23. 23.233 + 481 =
24. 24.306 + 473 =
25. 25.567 − 276 =
26. 26.258 + 438 =
27. 27.340 + 359 =
28. 28.580 − 427 =
29. 29.200 + 276 =
30. 30.538 + 177 =
31. 31.809 − 155 =
32. 32.531 − 305 =
33. 33.965 − 388 =
34. 34.775 − 553 =
35. 35.563 − 129 =
36. 36.895 − 259 =
37. 37.130 + 237 =
38. 38.288 + 182 =
39. 39.671 + 154 =
40. 40.415 + 129 =

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