3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 347 · 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. 1.570 + 369 =
2. 2.397 + 569 =
3. 3.762 + 252 =
4. 4.236 + 427 =
5. 5.690 − 485 =
6. 6.511 + 237 =
7. 7.476 + 139 =
8. 8.764 + 228 =
9. 9.892 − 647 =
10. 10.249 + 298 =
11. 11.505 + 173 =
12. 12.144 + 418 =
13. 13.825 − 461 =
14. 14.524 − 258 =
15. 15.331 + 677 =
16. 16.418 + 145 =
17. 17.693 + 411 =
18. 18.758 + 567 =
19. 19.589 − 379 =
20. 20.884 − 603 =
21. 21.574 + 268 =
22. 22.754 + 364 =
23. 23.517 + 618 =
24. 24.936 − 452 =
25. 25.665 + 677 =
26. 26.755 + 523 =
27. 27.526 + 456 =
28. 28.693 + 522 =
29. 29.735 + 243 =
30. 30.555 + 137 =
31. 31.590 + 611 =
32. 32.673 − 401 =
33. 33.510 + 186 =
34. 34.802 − 608 =
35. 35.683 + 401 =
36. 36.552 − 132 =
37. 37.428 − 196 =
38. 38.223 + 528 =
39. 39.548 − 264 =
40. 40.378 + 628 =

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