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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 61 · 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. 1.445 + 622 =
  2. 2.641 + 422 =
  3. 3.367 + 681 =
  4. 4.642 + 499 =
  5. 5.306 + 421 =
  6. 6.623 + 312 =
  7. 7.769 + 148 =
  8. 8.680 − 214 =
  9. 9.846 − 496 =
  10. 10.745 + 441 =
  11. 11.519 + 611 =
  12. 12.770 − 479 =
  13. 13.532 + 357 =
  14. 14.700 + 207 =
  15. 15.279 + 677 =
  16. 16.560 − 218 =
  17. 17.628 + 531 =
  18. 18.504 − 342 =
  19. 19.318 + 202 =
  20. 20.321 + 263 =
  21. 21.535 + 606 =
  22. 22.541 − 321 =
  23. 23.581 − 253 =
  24. 24.715 − 511 =
  25. 25.273 + 428 =
  26. 26.280 + 649 =
  27. 27.161 + 201 =
  28. 28.651 − 257 =
  29. 29.676 − 451 =
  30. 30.461 − 201 =
  31. 31.781 + 447 =
  32. 32.453 + 269 =
  33. 33.989 − 284 =
  34. 34.596 − 419 =
  35. 35.915 − 184 =
  36. 36.428 + 383 =
  37. 37.481 − 116 =
  38. 38.704 − 384 =
  39. 39.631 + 253 =
  40. 40.157 + 596 =

Answer key

  1. 1067
  2. 1063
  3. 1048
  4. 1141
  5. 727
  6. 935
  7. 917
  8. 466
  9. 350
  10. 1186
  11. 1130
  12. 291
  13. 889
  14. 907
  15. 956
  16. 342
  17. 1159
  18. 162
  19. 520
  20. 584
  21. 1141
  22. 220
  23. 328
  24. 204
  25. 701
  26. 929
  27. 362
  28. 394
  29. 225
  30. 260
  31. 1228
  32. 722
  33. 705
  34. 177
  35. 731
  36. 811
  37. 365
  38. 320
  39. 884
  40. 753

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