3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 58 · 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. 1.243 + 184 =
2. 2.628 + 201 =
3. 3.444 − 201 =
4. 4.424 + 273 =
5. 5.612 + 605 =
6. 6.570 + 439 =
7. 7.749 + 335 =
8. 8.735 + 175 =
9. 9.236 + 411 =
10. 10.447 + 685 =
11. 11.600 + 561 =
12. 12.184 + 373 =
13. 13.981 − 191 =
14. 14.422 + 298 =
15. 15.613 + 407 =
16. 16.830 − 316 =
17. 17.344 + 453 =
18. 18.262 + 531 =
19. 19.677 − 181 =
20. 20.545 − 435 =
21. 21.170 + 592 =
22. 22.754 + 541 =
23. 23.717 − 427 =
24. 24.522 − 341 =
25. 25.607 + 531 =
26. 26.914 − 321 =
27. 27.478 − 161 =
28. 28.710 − 298 =
29. 29.731 + 161 =
30. 30.489 − 143 =
31. 31.731 − 355 =
32. 32.846 − 624 =
33. 33.961 − 779 =
34. 34.574 + 666 =
35. 35.666 + 476 =
36. 36.433 − 301 =
37. 37.885 − 198 =
38. 38.305 + 143 =
39. 39.491 − 118 =
40. 40.624 − 382 =

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