3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 254 · 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. 1.459 + 583 =
2. 2.328 + 158 =
3. 3.507 + 466 =
4. 4.769 − 643 =
5. 5.955 − 853 =
6. 6.757 + 279 =
7. 7.828 − 202 =
8. 8.503 − 383 =
9. 9.393 + 161 =
10. 10.366 + 361 =
11. 11.547 + 279 =
12. 12.750 − 399 =
13. 13.426 + 469 =
14. 14.852 − 521 =
15. 15.434 − 174 =
16. 16.503 + 647 =
17. 17.129 + 651 =
18. 18.700 − 252 =
19. 19.284 + 491 =
20. 20.485 − 379 =
21. 21.489 + 368 =
22. 22.577 − 206 =
23. 23.481 + 594 =
24. 24.520 + 522 =
25. 25.306 + 198 =
26. 26.625 − 457 =
27. 27.837 − 239 =
28. 28.490 − 357 =
29. 29.489 + 639 =
30. 30.551 − 147 =
31. 31.650 − 131 =
32. 32.970 − 391 =
33. 33.954 − 215 =
34. 34.127 + 581 =
35. 35.452 + 514 =
36. 36.474 − 177 =
37. 37.498 − 182 =
38. 38.682 + 398 =
39. 39.738 − 621 =
40. 40.921 − 278 =

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