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3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 824 · 40 questions
TalentJR

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.

NameDateTime takenScore ___ / 40
  1. 1.340 + 201 =
  2. 2.561 − 146 =
  3. 3.126 + 661 =
  4. 4.688 − 475 =
  5. 5.626 − 281 =
  6. 6.342 + 664 =
  7. 7.175 + 199 =
  8. 8.979 − 282 =
  9. 9.733 + 363 =
  10. 10.217 + 305 =
  11. 11.191 + 156 =
  12. 12.448 + 329 =
  13. 13.439 − 167 =
  14. 14.345 + 289 =
  15. 15.549 + 331 =
  16. 16.599 − 412 =
  17. 17.259 + 339 =
  18. 18.420 − 249 =
  19. 19.156 + 473 =
  20. 20.177 + 303 =
  21. 21.296 + 202 =
  22. 22.936 − 631 =
  23. 23.302 + 131 =
  24. 24.681 + 239 =
  25. 25.590 − 137 =
  26. 26.124 + 559 =
  27. 27.680 + 318 =
  28. 28.848 − 502 =
  29. 29.758 + 516 =
  30. 30.782 + 262 =
  31. 31.752 − 481 =
  32. 32.411 + 509 =
  33. 33.745 + 503 =
  34. 34.201 + 305 =
  35. 35.544 − 262 =
  36. 36.538 − 253 =
  37. 37.701 − 213 =
  38. 38.726 + 269 =
  39. 39.508 − 209 =
  40. 40.287 + 555 =

Answer key

  1. 541
  2. 415
  3. 787
  4. 213
  5. 345
  6. 1006
  7. 374
  8. 697
  9. 1096
  10. 522
  11. 347
  12. 777
  13. 272
  14. 634
  15. 880
  16. 187
  17. 598
  18. 171
  19. 629
  20. 480
  21. 498
  22. 305
  23. 433
  24. 920
  25. 453
  26. 683
  27. 998
  28. 346
  29. 1274
  30. 1044
  31. 271
  32. 920
  33. 1248
  34. 506
  35. 282
  36. 285
  37. 488
  38. 995
  39. 299
  40. 842

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