3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 394 · 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. 1.142 + 661 =
2. 2.556 − 216 =
3. 3.770 + 322 =
4. 4.772 + 601 =
5. 5.555 − 414 =
6. 6.462 + 184 =
7. 7.836 − 563 =
8. 8.488 + 188 =
9. 9.773 + 122 =
10. 10.538 + 505 =
11. 11.496 + 176 =
12. 12.231 + 431 =
13. 13.569 + 601 =
14. 14.390 + 638 =
15. 15.896 − 506 =
16. 16.166 + 561 =
17. 17.559 − 201 =
18. 18.802 − 269 =
19. 19.370 + 191 =
20. 20.253 + 157 =
21. 21.780 − 437 =
22. 22.748 + 169 =
23. 23.705 − 574 =
24. 24.609 − 364 =
25. 25.989 − 122 =
26. 26.608 − 372 =
27. 27.725 − 325 =
28. 28.858 − 341 =
29. 29.270 + 232 =
30. 30.312 + 169 =
31. 31.613 + 543 =
32. 32.481 − 186 =
33. 33.314 + 442 =
34. 34.958 − 781 =
35. 35.666 − 186 =
36. 36.938 − 326 =
37. 37.707 − 326 =
38. 38.660 − 228 =
39. 39.611 + 609 =
40. 40.311 + 129 =

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