3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 998 · 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. 1.318 + 651 =
2. 2.780 − 318 =
3. 3.526 − 412 =
4. 4.415 − 216 =
5. 5.296 + 125 =
6. 6.192 + 663 =
7. 7.947 − 231 =
8. 8.533 − 221 =
9. 9.899 − 231 =
10. 10.244 + 539 =
11. 11.644 + 153 =
12. 12.488 + 142 =
13. 13.715 + 511 =
14. 14.275 + 191 =
15. 15.204 + 522 =
16. 16.585 − 206 =
17. 17.636 + 195 =
18. 18.126 + 223 =
19. 19.848 − 644 =
20. 20.457 − 276 =
21. 21.606 − 421 =
22. 22.757 − 238 =
23. 23.756 + 431 =
24. 24.898 − 428 =
25. 25.870 − 514 =
26. 26.595 − 131 =
27. 27.527 + 176 =
28. 28.503 + 282 =
29. 29.210 + 161 =
30. 30.737 + 162 =
31. 31.428 − 314 =
32. 32.498 + 121 =
33. 33.680 + 489 =
34. 34.470 + 617 =
35. 35.676 + 121 =
36. 36.229 + 394 =
37. 37.471 + 411 =
38. 38.809 − 133 =
39. 39.988 − 202 =
40. 40.576 − 189 =

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