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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 336 · 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. 1.786 − 412 =
  2. 2.978 − 728 =
  3. 3.690 − 146 =
  4. 4.590 + 613 =
  5. 5.420 − 136 =
  6. 6.262 + 193 =
  7. 7.496 − 171 =
  8. 8.765 − 241 =
  9. 9.276 + 237 =
  10. 10.598 − 291 =
  11. 11.486 + 516 =
  12. 12.654 − 508 =
  13. 13.587 + 418 =
  14. 14.460 + 607 =
  15. 15.447 + 168 =
  16. 16.396 + 515 =
  17. 17.714 + 417 =
  18. 18.269 + 493 =
  19. 19.301 + 351 =
  20. 20.386 + 669 =
  21. 21.447 − 169 =
  22. 22.181 + 354 =
  23. 23.433 − 171 =
  24. 24.747 − 632 =
  25. 25.251 + 231 =
  26. 26.852 − 711 =
  27. 27.750 + 579 =
  28. 28.636 − 234 =
  29. 29.705 + 301 =
  30. 30.593 + 188 =
  31. 31.412 + 181 =
  32. 32.482 + 422 =
  33. 33.771 + 241 =
  34. 34.131 + 184 =
  35. 35.557 − 168 =
  36. 36.135 + 597 =
  37. 37.720 + 134 =
  38. 38.627 − 299 =
  39. 39.727 − 235 =
  40. 40.219 + 207 =

Answer key

  1. 374
  2. 250
  3. 544
  4. 1203
  5. 284
  6. 455
  7. 325
  8. 524
  9. 513
  10. 307
  11. 1002
  12. 146
  13. 1005
  14. 1067
  15. 615
  16. 911
  17. 1131
  18. 762
  19. 652
  20. 1055
  21. 278
  22. 535
  23. 262
  24. 115
  25. 482
  26. 141
  27. 1329
  28. 402
  29. 1006
  30. 781
  31. 593
  32. 904
  33. 1012
  34. 315
  35. 389
  36. 732
  37. 854
  38. 328
  39. 492
  40. 426

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