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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 609 · 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. 1.386 + 504 =
  2. 2.128 + 471 =
  3. 3.652 − 351 =
  4. 4.240 + 121 =
  5. 5.128 + 179 =
  6. 6.498 − 271 =
  7. 7.356 + 259 =
  8. 8.398 + 552 =
  9. 9.590 − 488 =
  10. 10.377 + 201 =
  11. 11.619 + 643 =
  12. 12.653 − 451 =
  13. 13.559 + 489 =
  14. 14.543 − 382 =
  15. 15.878 − 258 =
  16. 16.435 − 243 =
  17. 17.333 + 347 =
  18. 18.525 + 187 =
  19. 19.973 − 702 =
  20. 20.519 − 274 =
  21. 21.376 + 337 =
  22. 22.680 − 578 =
  23. 23.453 + 357 =
  24. 24.739 − 135 =
  25. 25.413 + 119 =
  26. 26.217 + 377 =
  27. 27.487 − 174 =
  28. 28.691 + 165 =
  29. 29.287 + 461 =
  30. 30.210 + 349 =
  31. 31.683 − 163 =
  32. 32.326 + 581 =
  33. 33.609 + 388 =
  34. 34.527 − 138 =
  35. 35.242 + 405 =
  36. 36.168 + 198 =
  37. 37.552 − 331 =
  38. 38.417 − 169 =
  39. 39.246 + 128 =
  40. 40.651 + 241 =

Answer key

  1. 890
  2. 599
  3. 301
  4. 361
  5. 307
  6. 227
  7. 615
  8. 950
  9. 102
  10. 578
  11. 1262
  12. 202
  13. 1048
  14. 161
  15. 620
  16. 192
  17. 680
  18. 712
  19. 271
  20. 245
  21. 713
  22. 102
  23. 810
  24. 604
  25. 532
  26. 594
  27. 313
  28. 856
  29. 748
  30. 559
  31. 520
  32. 907
  33. 997
  34. 389
  35. 647
  36. 366
  37. 221
  38. 248
  39. 374
  40. 892

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