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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 406 · 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. 1.746 − 498 =
  2. 2.789 + 281 =
  3. 3.749 + 602 =
  4. 4.312 + 333 =
  5. 5.595 + 154 =
  6. 6.252 + 602 =
  7. 7.241 + 391 =
  8. 8.199 + 439 =
  9. 9.750 − 599 =
  10. 10.566 − 435 =
  11. 11.189 + 143 =
  12. 12.515 − 129 =
  13. 13.239 + 559 =
  14. 14.222 + 391 =
  15. 15.666 + 622 =
  16. 16.708 − 235 =
  17. 17.322 + 686 =
  18. 18.658 − 442 =
  19. 19.678 + 577 =
  20. 20.534 + 211 =
  21. 21.209 + 623 =
  22. 22.479 + 369 =
  23. 23.624 − 181 =
  24. 24.877 − 345 =
  25. 25.203 + 134 =
  26. 26.429 − 129 =
  27. 27.642 − 421 =
  28. 28.643 − 168 =
  29. 29.720 − 279 =
  30. 30.376 + 197 =
  31. 31.502 − 321 =
  32. 32.291 + 172 =
  33. 33.459 − 356 =
  34. 34.410 + 521 =
  35. 35.747 + 611 =
  36. 36.528 − 253 =
  37. 37.634 + 532 =
  38. 38.347 + 441 =
  39. 39.304 + 254 =
  40. 40.629 + 671 =

Answer key

  1. 248
  2. 1070
  3. 1351
  4. 645
  5. 749
  6. 854
  7. 632
  8. 638
  9. 151
  10. 131
  11. 332
  12. 386
  13. 798
  14. 613
  15. 1288
  16. 473
  17. 1008
  18. 216
  19. 1255
  20. 745
  21. 832
  22. 848
  23. 443
  24. 532
  25. 337
  26. 300
  27. 221
  28. 475
  29. 441
  30. 573
  31. 181
  32. 463
  33. 103
  34. 931
  35. 1358
  36. 275
  37. 1166
  38. 788
  39. 558
  40. 1300

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