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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 675 · 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. 1.690 + 257 =
  2. 2.289 + 239 =
  3. 3.178 + 571 =
  4. 4.473 − 279 =
  5. 5.518 − 412 =
  6. 6.514 − 172 =
  7. 7.474 − 262 =
  8. 8.567 + 429 =
  9. 9.633 − 452 =
  10. 10.485 − 336 =
  11. 11.721 + 637 =
  12. 12.653 − 503 =
  13. 13.529 − 367 =
  14. 14.870 − 284 =
  15. 15.167 + 152 =
  16. 16.208 + 443 =
  17. 17.694 + 538 =
  18. 18.334 + 124 =
  19. 19.516 − 271 =
  20. 20.209 + 133 =
  21. 21.709 − 267 =
  22. 22.529 + 441 =
  23. 23.164 + 429 =
  24. 24.808 − 541 =
  25. 25.633 + 606 =
  26. 26.546 + 201 =
  27. 27.483 + 235 =
  28. 28.304 + 637 =
  29. 29.789 + 351 =
  30. 30.794 − 157 =
  31. 31.672 − 475 =
  32. 32.457 − 165 =
  33. 33.717 − 253 =
  34. 34.678 − 532 =
  35. 35.539 − 321 =
  36. 36.537 + 194 =
  37. 37.622 + 124 =
  38. 38.505 − 376 =
  39. 39.731 − 591 =
  40. 40.762 + 127 =

Answer key

  1. 947
  2. 528
  3. 749
  4. 194
  5. 106
  6. 342
  7. 212
  8. 996
  9. 181
  10. 149
  11. 1358
  12. 150
  13. 162
  14. 586
  15. 319
  16. 651
  17. 1232
  18. 458
  19. 245
  20. 342
  21. 442
  22. 970
  23. 593
  24. 267
  25. 1239
  26. 747
  27. 718
  28. 941
  29. 1140
  30. 637
  31. 197
  32. 292
  33. 464
  34. 146
  35. 218
  36. 731
  37. 746
  38. 129
  39. 140
  40. 889

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