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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 672 · 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. 1.426 + 681 =
  2. 2.852 − 695 =
  3. 3.266 + 479 =
  4. 4.414 − 211 =
  5. 5.492 + 591 =
  6. 6.502 + 451 =
  7. 7.400 + 641 =
  8. 8.720 + 346 =
  9. 9.297 + 374 =
  10. 10.318 + 167 =
  11. 11.346 + 549 =
  12. 12.671 − 136 =
  13. 13.474 − 301 =
  14. 14.166 + 345 =
  15. 15.785 + 412 =
  16. 16.967 − 862 =
  17. 17.274 + 478 =
  18. 18.675 − 429 =
  19. 19.561 + 327 =
  20. 20.697 + 396 =
  21. 21.515 − 277 =
  22. 22.706 − 334 =
  23. 23.382 + 299 =
  24. 24.853 − 658 =
  25. 25.230 + 562 =
  26. 26.362 + 664 =
  27. 27.533 + 614 =
  28. 28.675 + 429 =
  29. 29.158 + 219 =
  30. 30.235 + 503 =
  31. 31.609 − 199 =
  32. 32.606 − 168 =
  33. 33.468 − 148 =
  34. 34.954 − 245 =
  35. 35.215 + 225 =
  36. 36.643 + 261 =
  37. 37.299 + 203 =
  38. 38.622 − 452 =
  39. 39.187 + 275 =
  40. 40.639 + 508 =

Answer key

  1. 1107
  2. 157
  3. 745
  4. 203
  5. 1083
  6. 953
  7. 1041
  8. 1066
  9. 671
  10. 485
  11. 895
  12. 535
  13. 173
  14. 511
  15. 1197
  16. 105
  17. 752
  18. 246
  19. 888
  20. 1093
  21. 238
  22. 372
  23. 681
  24. 195
  25. 792
  26. 1026
  27. 1147
  28. 1104
  29. 377
  30. 738
  31. 410
  32. 438
  33. 320
  34. 709
  35. 440
  36. 904
  37. 502
  38. 170
  39. 462
  40. 1147

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