3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 521 · 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. 1.639 + 504 =
2. 2.780 + 121 =
3. 3.617 − 215 =
4. 4.249 + 544 =
5. 5.426 + 421 =
6. 6.480 − 297 =
7. 7.621 + 425 =
8. 8.385 + 486 =
9. 9.887 − 689 =
10. 10.556 − 439 =
11. 11.776 − 575 =
12. 12.512 + 623 =
13. 13.965 − 279 =
14. 14.863 − 728 =
15. 15.465 − 364 =
16. 16.271 + 294 =
17. 17.479 − 125 =
18. 18.648 + 171 =
19. 19.913 − 769 =
20. 20.403 + 245 =
21. 21.494 − 391 =
22. 22.888 − 453 =
23. 23.520 − 163 =
24. 24.636 + 604 =
25. 25.772 + 651 =
26. 26.929 − 121 =
27. 27.398 + 494 =
28. 28.593 + 209 =
29. 29.889 − 251 =
30. 30.751 + 673 =
31. 31.872 − 227 =
32. 32.189 + 321 =
33. 33.615 + 647 =
34. 34.543 − 336 =
35. 35.692 − 168 =
36. 36.835 − 601 =
37. 37.513 − 261 =
38. 38.646 − 197 =
39. 39.384 + 582 =
40. 40.250 + 408 =

Free mental maths lessons, practice and worksheets at talentjr.in/mental-maths