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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 852 · 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. 1.311 + 261 =
  2. 2.905 − 716 =
  3. 3.620 − 118 =
  4. 4.748 + 112 =
  5. 5.894 − 121 =
  6. 6.930 − 158 =
  7. 7.591 + 253 =
  8. 8.691 − 357 =
  9. 9.467 − 291 =
  10. 10.730 − 347 =
  11. 11.947 − 841 =
  12. 12.757 − 521 =
  13. 13.532 + 397 =
  14. 14.499 + 191 =
  15. 15.435 − 247 =
  16. 16.681 − 521 =
  17. 17.959 − 231 =
  18. 18.739 + 187 =
  19. 19.200 + 423 =
  20. 20.707 − 231 =
  21. 21.726 − 289 =
  22. 22.982 − 634 =
  23. 23.548 − 242 =
  24. 24.601 − 478 =
  25. 25.301 + 661 =
  26. 26.413 − 144 =
  27. 27.545 − 361 =
  28. 28.473 + 661 =
  29. 29.629 − 121 =
  30. 30.173 + 128 =
  31. 31.424 + 381 =
  32. 32.243 + 319 =
  33. 33.507 + 197 =
  34. 34.446 − 274 =
  35. 35.492 + 292 =
  36. 36.413 + 326 =
  37. 37.225 + 251 =
  38. 38.611 − 444 =
  39. 39.879 − 485 =
  40. 40.165 + 495 =

Answer key

  1. 572
  2. 189
  3. 502
  4. 860
  5. 773
  6. 772
  7. 844
  8. 334
  9. 176
  10. 383
  11. 106
  12. 236
  13. 929
  14. 690
  15. 188
  16. 160
  17. 728
  18. 926
  19. 623
  20. 476
  21. 437
  22. 348
  23. 306
  24. 123
  25. 962
  26. 269
  27. 184
  28. 1134
  29. 508
  30. 301
  31. 805
  32. 562
  33. 704
  34. 172
  35. 784
  36. 739
  37. 476
  38. 167
  39. 394
  40. 660

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