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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 559 · 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. 1.222 + 122 =
  2. 2.704 − 327 =
  3. 3.501 − 269 =
  4. 4.502 + 357 =
  5. 5.952 − 781 =
  6. 6.255 + 339 =
  7. 7.460 − 235 =
  8. 8.780 + 439 =
  9. 9.499 − 137 =
  10. 10.692 + 114 =
  11. 11.788 − 381 =
  12. 12.453 + 548 =
  13. 13.547 − 178 =
  14. 14.558 − 172 =
  15. 15.255 + 311 =
  16. 16.674 + 517 =
  17. 17.186 + 515 =
  18. 18.428 + 354 =
  19. 19.329 + 399 =
  20. 20.307 + 292 =
  21. 21.467 + 322 =
  22. 22.658 + 657 =
  23. 23.479 + 151 =
  24. 24.308 + 225 =
  25. 25.530 − 411 =
  26. 26.874 − 697 =
  27. 27.711 + 402 =
  28. 28.504 − 336 =
  29. 29.390 + 161 =
  30. 30.691 − 203 =
  31. 31.415 − 131 =
  32. 32.891 − 225 =
  33. 33.754 − 265 =
  34. 34.563 + 284 =
  35. 35.668 − 534 =
  36. 36.789 + 501 =
  37. 37.249 + 237 =
  38. 38.725 + 487 =
  39. 39.351 + 674 =
  40. 40.700 + 121 =

Answer key

  1. 344
  2. 377
  3. 232
  4. 859
  5. 171
  6. 594
  7. 225
  8. 1219
  9. 362
  10. 806
  11. 407
  12. 1001
  13. 369
  14. 386
  15. 566
  16. 1191
  17. 701
  18. 782
  19. 728
  20. 599
  21. 789
  22. 1315
  23. 630
  24. 533
  25. 119
  26. 177
  27. 1113
  28. 168
  29. 551
  30. 488
  31. 284
  32. 666
  33. 489
  34. 847
  35. 134
  36. 1290
  37. 486
  38. 1212
  39. 1025
  40. 821

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