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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 408 · 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. 1.153 + 234 =
  2. 2.204 + 191 =
  3. 3.983 − 618 =
  4. 4.675 − 407 =
  5. 5.347 + 219 =
  6. 6.719 − 417 =
  7. 7.565 + 167 =
  8. 8.788 + 453 =
  9. 9.530 − 387 =
  10. 10.620 + 374 =
  11. 11.538 + 417 =
  12. 12.959 − 745 =
  13. 13.820 − 513 =
  14. 14.741 − 152 =
  15. 15.479 + 659 =
  16. 16.517 + 569 =
  17. 17.189 + 511 =
  18. 18.719 + 268 =
  19. 19.240 + 518 =
  20. 20.152 + 286 =
  21. 21.735 − 623 =
  22. 22.802 − 274 =
  23. 23.503 + 228 =
  24. 24.227 + 275 =
  25. 25.416 − 215 =
  26. 26.690 + 187 =
  27. 27.389 + 611 =
  28. 28.752 + 354 =
  29. 29.560 − 326 =
  30. 30.360 + 221 =
  31. 31.200 + 384 =
  32. 32.492 + 561 =
  33. 33.465 + 368 =
  34. 34.430 − 216 =
  35. 35.630 + 231 =
  36. 36.213 + 345 =
  37. 37.442 + 301 =
  38. 38.486 + 214 =
  39. 39.450 + 305 =
  40. 40.595 − 483 =

Answer key

  1. 387
  2. 395
  3. 365
  4. 268
  5. 566
  6. 302
  7. 732
  8. 1241
  9. 143
  10. 994
  11. 955
  12. 214
  13. 307
  14. 589
  15. 1138
  16. 1086
  17. 700
  18. 987
  19. 758
  20. 438
  21. 112
  22. 528
  23. 731
  24. 502
  25. 201
  26. 877
  27. 1000
  28. 1106
  29. 234
  30. 581
  31. 584
  32. 1053
  33. 833
  34. 214
  35. 861
  36. 558
  37. 743
  38. 700
  39. 755
  40. 112

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