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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 164 · 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. 1.418 + 174 =
  2. 2.667 + 471 =
  3. 3.418 − 152 =
  4. 4.918 − 399 =
  5. 5.676 − 316 =
  6. 6.811 − 266 =
  7. 7.743 − 401 =
  8. 8.149 + 447 =
  9. 9.717 + 539 =
  10. 10.439 − 169 =
  11. 11.367 + 495 =
  12. 12.916 − 519 =
  13. 13.513 + 343 =
  14. 14.133 + 272 =
  15. 15.843 − 392 =
  16. 16.975 − 474 =
  17. 17.256 + 491 =
  18. 18.435 − 161 =
  19. 19.598 + 611 =
  20. 20.529 + 259 =
  21. 21.172 + 385 =
  22. 22.888 − 783 =
  23. 23.191 + 594 =
  24. 24.749 − 267 =
  25. 25.614 + 221 =
  26. 26.692 + 158 =
  27. 27.450 + 465 =
  28. 28.545 − 327 =
  29. 29.712 + 641 =
  30. 30.211 + 453 =
  31. 31.770 + 451 =
  32. 32.475 + 519 =
  33. 33.515 + 265 =
  34. 34.718 − 171 =
  35. 35.962 − 511 =
  36. 36.153 + 295 =
  37. 37.335 + 469 =
  38. 38.555 − 199 =
  39. 39.649 + 198 =
  40. 40.127 + 209 =

Answer key

  1. 592
  2. 1138
  3. 266
  4. 519
  5. 360
  6. 545
  7. 342
  8. 596
  9. 1256
  10. 270
  11. 862
  12. 397
  13. 856
  14. 405
  15. 451
  16. 501
  17. 747
  18. 274
  19. 1209
  20. 788
  21. 557
  22. 105
  23. 785
  24. 482
  25. 835
  26. 850
  27. 915
  28. 218
  29. 1353
  30. 664
  31. 1221
  32. 994
  33. 780
  34. 547
  35. 451
  36. 448
  37. 804
  38. 356
  39. 847
  40. 336

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