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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 536 · 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. 1.744 + 121 =
  2. 2.402 + 228 =
  3. 3.643 + 393 =
  4. 4.706 − 319 =
  5. 5.934 − 302 =
  6. 6.656 − 481 =
  7. 7.729 + 667 =
  8. 8.706 + 316 =
  9. 9.952 − 154 =
  10. 10.497 − 346 =
  11. 11.460 − 165 =
  12. 12.957 − 452 =
  13. 13.976 − 202 =
  14. 14.360 + 338 =
  15. 15.669 + 246 =
  16. 16.259 + 222 =
  17. 17.498 − 175 =
  18. 18.494 + 531 =
  19. 19.608 − 252 =
  20. 20.502 − 321 =
  21. 21.746 − 355 =
  22. 22.661 − 176 =
  23. 23.679 + 272 =
  24. 24.180 + 201 =
  25. 25.239 + 351 =
  26. 26.742 − 332 =
  27. 27.668 + 327 =
  28. 28.194 + 644 =
  29. 29.618 − 497 =
  30. 30.348 + 325 =
  31. 31.378 + 601 =
  32. 32.260 + 301 =
  33. 33.495 − 182 =
  34. 34.433 − 278 =
  35. 35.692 + 522 =
  36. 36.274 + 355 =
  37. 37.635 + 184 =
  38. 38.582 + 179 =
  39. 39.274 + 208 =
  40. 40.620 + 139 =

Answer key

  1. 865
  2. 630
  3. 1036
  4. 387
  5. 632
  6. 175
  7. 1396
  8. 1022
  9. 798
  10. 151
  11. 295
  12. 505
  13. 774
  14. 698
  15. 915
  16. 481
  17. 323
  18. 1025
  19. 356
  20. 181
  21. 391
  22. 485
  23. 951
  24. 381
  25. 590
  26. 410
  27. 995
  28. 838
  29. 121
  30. 673
  31. 979
  32. 561
  33. 313
  34. 155
  35. 1214
  36. 629
  37. 819
  38. 761
  39. 482
  40. 759

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