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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 417 · 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. 1.277 + 421 =
  2. 2.899 − 119 =
  3. 3.310 + 264 =
  4. 4.373 + 434 =
  5. 5.463 − 235 =
  6. 6.616 − 263 =
  7. 7.488 − 313 =
  8. 8.381 + 126 =
  9. 9.126 + 479 =
  10. 10.427 + 591 =
  11. 11.416 − 202 =
  12. 12.528 − 312 =
  13. 13.737 + 581 =
  14. 14.642 + 571 =
  15. 15.870 − 253 =
  16. 16.720 − 501 =
  17. 17.588 − 295 =
  18. 18.439 − 305 =
  19. 19.257 + 291 =
  20. 20.678 − 341 =
  21. 21.405 + 381 =
  22. 22.243 + 408 =
  23. 23.676 + 256 =
  24. 24.800 − 354 =
  25. 25.136 + 176 =
  26. 26.596 − 383 =
  27. 27.592 − 279 =
  28. 28.673 − 244 =
  29. 29.221 + 212 =
  30. 30.625 − 167 =
  31. 31.574 − 158 =
  32. 32.745 − 195 =
  33. 33.283 + 211 =
  34. 34.707 − 201 =
  35. 35.575 − 188 =
  36. 36.549 + 683 =
  37. 37.322 + 338 =
  38. 38.623 − 447 =
  39. 39.488 − 305 =
  40. 40.412 − 191 =

Answer key

  1. 698
  2. 780
  3. 574
  4. 807
  5. 228
  6. 353
  7. 175
  8. 507
  9. 605
  10. 1018
  11. 214
  12. 216
  13. 1318
  14. 1213
  15. 617
  16. 219
  17. 293
  18. 134
  19. 548
  20. 337
  21. 786
  22. 651
  23. 932
  24. 446
  25. 312
  26. 213
  27. 313
  28. 429
  29. 433
  30. 458
  31. 416
  32. 550
  33. 494
  34. 506
  35. 387
  36. 1232
  37. 660
  38. 176
  39. 183
  40. 221

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