3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 43 · 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. 1.682 + 229 =
2. 2.624 + 242 =
3. 3.445 + 632 =
4. 4.671 + 582 =
5. 5.928 − 336 =
6. 6.727 − 554 =
7. 7.769 + 615 =
8. 8.379 + 261 =
9. 9.755 − 401 =
10. 10.466 + 688 =
11. 11.948 − 583 =
12. 12.643 − 421 =
13. 13.534 + 327 =
14. 14.428 − 167 =
15. 15.500 − 335 =
16. 16.576 − 213 =
17. 17.389 + 196 =
18. 18.434 − 249 =
19. 19.678 − 361 =
20. 20.977 − 541 =
21. 21.438 − 201 =
22. 22.510 − 274 =
23. 23.677 + 684 =
24. 24.856 − 546 =
25. 25.449 − 302 =
26. 26.622 − 291 =
27. 27.450 + 462 =
28. 28.454 − 135 =
29. 29.532 − 231 =
30. 30.491 − 202 =
31. 31.809 − 374 =
32. 32.427 − 181 =
33. 33.143 + 251 =
34. 34.587 − 266 =
35. 35.489 − 184 =
36. 36.650 − 512 =
37. 37.294 + 538 =
38. 38.672 − 116 =
39. 39.283 + 594 =
40. 40.415 − 119 =

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