3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 986 · 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. 1.406 + 114 =
2. 2.376 + 585 =
3. 3.144 + 168 =
4. 4.799 − 515 =
5. 5.922 − 124 =
6. 6.636 + 235 =
7. 7.851 − 149 =
8. 8.675 + 273 =
9. 9.286 + 456 =
10. 10.223 + 671 =
11. 11.455 + 439 =
12. 12.731 − 297 =
13. 13.679 − 175 =
14. 14.197 + 449 =
15. 15.447 − 311 =
16. 16.643 + 181 =
17. 17.313 + 316 =
18. 18.844 − 259 =
19. 19.726 + 186 =
20. 20.751 + 279 =
21. 21.874 − 452 =
22. 22.594 + 234 =
23. 23.854 − 364 =
24. 24.940 − 124 =
25. 25.623 − 468 =
26. 26.481 − 371 =
27. 27.663 + 569 =
28. 28.450 − 191 =
29. 29.429 − 137 =
30. 30.850 − 581 =
31. 31.681 + 378 =
32. 32.561 − 392 =
33. 33.131 + 352 =
34. 34.286 + 678 =
35. 35.727 − 127 =
36. 36.736 + 419 =
37. 37.698 − 168 =
38. 38.578 + 382 =
39. 39.526 − 174 =
40. 40.837 − 147 =

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