3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 196 · 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. 1.128 + 595 =
2. 2.822 − 465 =
3. 3.179 + 451 =
4. 4.803 − 429 =
5. 5.714 − 312 =
6. 6.502 − 297 =
7. 7.517 − 317 =
8. 8.874 − 482 =
9. 9.236 + 195 =
10. 10.465 − 191 =
11. 11.644 + 659 =
12. 12.545 − 341 =
13. 13.660 − 237 =
14. 14.207 + 561 =
15. 15.305 + 574 =
16. 16.838 − 464 =
17. 17.412 − 298 =
18. 18.843 − 319 =
19. 19.845 − 144 =
20. 20.640 − 527 =
21. 21.552 + 475 =
22. 22.657 − 431 =
23. 23.659 + 517 =
24. 24.185 + 651 =
25. 25.703 + 175 =
26. 26.399 + 173 =
27. 27.837 − 488 =
28. 28.805 − 556 =
29. 29.878 − 479 =
30. 30.300 + 431 =
31. 31.158 + 233 =
32. 32.545 − 442 =
33. 33.726 − 431 =
34. 34.567 − 239 =
35. 35.714 + 182 =
36. 36.447 − 346 =
37. 37.217 + 662 =
38. 38.389 + 205 =
39. 39.490 − 364 =
40. 40.839 − 162 =

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