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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 640 · 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. 1.488 − 251 =
  2. 2.656 − 164 =
  3. 3.672 + 478 =
  4. 4.907 − 691 =
  5. 5.919 − 571 =
  6. 6.244 + 163 =
  7. 7.693 + 325 =
  8. 8.873 − 711 =
  9. 9.678 − 155 =
  10. 10.510 − 397 =
  11. 11.554 − 201 =
  12. 12.212 + 375 =
  13. 13.812 − 686 =
  14. 14.530 + 396 =
  15. 15.851 − 561 =
  16. 16.626 + 539 =
  17. 17.139 + 534 =
  18. 18.721 + 236 =
  19. 19.619 + 381 =
  20. 20.125 + 182 =
  21. 21.675 + 671 =
  22. 22.396 + 545 =
  23. 23.570 − 332 =
  24. 24.258 + 249 =
  25. 25.318 + 281 =
  26. 26.776 − 522 =
  27. 27.710 + 437 =
  28. 28.727 − 572 =
  29. 29.654 − 289 =
  30. 30.142 + 565 =
  31. 31.558 − 271 =
  32. 32.831 − 141 =
  33. 33.137 + 289 =
  34. 34.771 + 392 =
  35. 35.206 + 263 =
  36. 36.387 + 209 =
  37. 37.869 − 125 =
  38. 38.626 + 171 =
  39. 39.380 + 571 =
  40. 40.607 + 315 =

Answer key

  1. 237
  2. 492
  3. 1150
  4. 216
  5. 348
  6. 407
  7. 1018
  8. 162
  9. 523
  10. 113
  11. 353
  12. 587
  13. 126
  14. 926
  15. 290
  16. 1165
  17. 673
  18. 957
  19. 1000
  20. 307
  21. 1346
  22. 941
  23. 238
  24. 507
  25. 599
  26. 254
  27. 1147
  28. 155
  29. 365
  30. 707
  31. 287
  32. 690
  33. 426
  34. 1163
  35. 469
  36. 596
  37. 744
  38. 797
  39. 951
  40. 922

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