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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 690 · 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. 1.315 + 234 =
  2. 2.585 − 421 =
  3. 3.259 + 495 =
  4. 4.537 + 245 =
  5. 5.202 + 182 =
  6. 6.965 − 641 =
  7. 7.193 + 138 =
  8. 8.984 − 132 =
  9. 9.388 + 501 =
  10. 10.427 + 197 =
  11. 11.433 + 527 =
  12. 12.726 + 337 =
  13. 13.416 − 259 =
  14. 14.709 − 342 =
  15. 15.921 − 137 =
  16. 16.699 − 368 =
  17. 17.688 − 161 =
  18. 18.714 + 409 =
  19. 19.496 − 294 =
  20. 20.573 − 404 =
  21. 21.355 + 681 =
  22. 22.672 + 161 =
  23. 23.570 − 454 =
  24. 24.834 − 204 =
  25. 25.483 + 381 =
  26. 26.678 + 577 =
  27. 27.430 + 372 =
  28. 28.572 − 373 =
  29. 29.650 − 181 =
  30. 30.182 + 191 =
  31. 31.897 − 171 =
  32. 32.418 + 267 =
  33. 33.894 − 321 =
  34. 34.229 + 238 =
  35. 35.639 + 449 =
  36. 36.962 − 817 =
  37. 37.761 − 143 =
  38. 38.490 − 291 =
  39. 39.564 + 641 =
  40. 40.203 + 266 =

Answer key

  1. 549
  2. 164
  3. 754
  4. 782
  5. 384
  6. 324
  7. 331
  8. 852
  9. 889
  10. 624
  11. 960
  12. 1063
  13. 157
  14. 367
  15. 784
  16. 331
  17. 527
  18. 1123
  19. 202
  20. 169
  21. 1036
  22. 833
  23. 116
  24. 630
  25. 864
  26. 1255
  27. 802
  28. 199
  29. 469
  30. 373
  31. 726
  32. 685
  33. 573
  34. 467
  35. 1088
  36. 145
  37. 618
  38. 199
  39. 1205
  40. 469

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