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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 991 · 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. 1.181 + 131 =
  2. 2.152 + 632 =
  3. 3.505 − 201 =
  4. 4.524 + 221 =
  5. 5.194 + 291 =
  6. 6.292 + 542 =
  7. 7.265 + 514 =
  8. 8.431 + 142 =
  9. 9.494 + 553 =
  10. 10.183 + 601 =
  11. 11.843 − 673 =
  12. 12.164 + 328 =
  13. 13.572 − 469 =
  14. 14.445 + 159 =
  15. 15.547 − 217 =
  16. 16.623 − 152 =
  17. 17.172 + 161 =
  18. 18.162 + 188 =
  19. 19.639 + 267 =
  20. 20.761 + 594 =
  21. 21.720 + 378 =
  22. 22.905 − 197 =
  23. 23.539 − 183 =
  24. 24.231 + 162 =
  25. 25.802 − 521 =
  26. 26.532 + 537 =
  27. 27.445 − 118 =
  28. 28.799 − 154 =
  29. 29.809 − 228 =
  30. 30.714 − 397 =
  31. 31.415 − 303 =
  32. 32.849 − 358 =
  33. 33.765 + 288 =
  34. 34.551 + 611 =
  35. 35.456 − 224 =
  36. 36.500 − 215 =
  37. 37.361 + 462 =
  38. 38.322 + 313 =
  39. 39.543 + 348 =
  40. 40.326 + 457 =

Answer key

  1. 312
  2. 784
  3. 304
  4. 745
  5. 485
  6. 834
  7. 779
  8. 573
  9. 1047
  10. 784
  11. 170
  12. 492
  13. 103
  14. 604
  15. 330
  16. 471
  17. 333
  18. 350
  19. 906
  20. 1355
  21. 1098
  22. 708
  23. 356
  24. 393
  25. 281
  26. 1069
  27. 327
  28. 645
  29. 581
  30. 317
  31. 112
  32. 491
  33. 1053
  34. 1162
  35. 232
  36. 285
  37. 823
  38. 635
  39. 891
  40. 783

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