3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 661 · 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. 1.291 + 311 =
2. 2.940 − 393 =
3. 3.846 − 715 =
4. 4.760 − 138 =
5. 5.402 + 536 =
6. 6.671 − 359 =
7. 7.455 + 251 =
8. 8.153 + 291 =
9. 9.918 − 224 =
10. 10.738 + 598 =
11. 11.684 − 521 =
12. 12.758 − 124 =
13. 13.164 + 674 =
14. 14.885 − 759 =
15. 15.373 + 445 =
16. 16.267 + 607 =
17. 17.986 − 156 =
18. 18.199 + 521 =
19. 19.490 + 669 =
20. 20.531 − 219 =
21. 21.337 + 351 =
22. 22.244 + 546 =
23. 23.620 + 171 =
24. 24.441 − 172 =
25. 25.382 + 408 =
26. 26.330 + 131 =
27. 27.459 − 311 =
28. 28.192 + 675 =
29. 29.196 + 161 =
30. 30.973 − 553 =
31. 31.540 + 459 =
32. 32.355 + 267 =
33. 33.655 + 336 =
34. 34.825 − 385 =
35. 35.355 + 204 =
36. 36.550 + 661 =
37. 37.697 − 174 =
38. 38.202 + 225 =
39. 39.225 + 614 =
40. 40.782 − 607 =

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