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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 647 · 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. 1.123 + 533 =
  2. 2.905 − 199 =
  3. 3.460 − 198 =
  4. 4.658 − 328 =
  5. 5.643 − 255 =
  6. 6.504 − 154 =
  7. 7.553 + 471 =
  8. 8.685 − 439 =
  9. 9.623 + 492 =
  10. 10.512 − 372 =
  11. 11.840 − 659 =
  12. 12.231 + 443 =
  13. 13.489 + 444 =
  14. 14.730 − 151 =
  15. 15.740 + 509 =
  16. 16.587 − 274 =
  17. 17.402 + 661 =
  18. 18.629 − 404 =
  19. 19.553 + 278 =
  20. 20.533 − 419 =
  21. 21.530 + 401 =
  22. 22.637 − 194 =
  23. 23.307 + 152 =
  24. 24.125 + 283 =
  25. 25.357 + 125 =
  26. 26.677 + 131 =
  27. 27.567 − 309 =
  28. 28.362 + 679 =
  29. 29.535 − 416 =
  30. 30.916 − 159 =
  31. 31.872 − 748 =
  32. 32.735 − 574 =
  33. 33.616 + 264 =
  34. 34.530 − 181 =
  35. 35.480 + 201 =
  36. 36.640 + 596 =
  37. 37.721 + 204 =
  38. 38.205 + 326 =
  39. 39.186 + 674 =
  40. 40.619 − 431 =

Answer key

  1. 656
  2. 706
  3. 262
  4. 330
  5. 388
  6. 350
  7. 1024
  8. 246
  9. 1115
  10. 140
  11. 181
  12. 674
  13. 933
  14. 579
  15. 1249
  16. 313
  17. 1063
  18. 225
  19. 831
  20. 114
  21. 931
  22. 443
  23. 459
  24. 408
  25. 482
  26. 808
  27. 258
  28. 1041
  29. 119
  30. 757
  31. 124
  32. 161
  33. 880
  34. 349
  35. 681
  36. 1236
  37. 925
  38. 531
  39. 860
  40. 188

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