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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 739 · 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. 1.614 + 386 =
  2. 2.720 + 442 =
  3. 3.772 − 352 =
  4. 4.661 + 499 =
  5. 5.658 + 423 =
  6. 6.721 − 589 =
  7. 7.842 − 181 =
  8. 8.454 + 194 =
  9. 9.497 + 345 =
  10. 10.268 + 357 =
  11. 11.344 + 534 =
  12. 12.613 − 129 =
  13. 13.258 + 603 =
  14. 14.471 − 301 =
  15. 15.477 + 334 =
  16. 16.562 + 626 =
  17. 17.632 − 149 =
  18. 18.614 − 477 =
  19. 19.130 + 129 =
  20. 20.558 + 444 =
  21. 21.226 + 619 =
  22. 22.966 − 673 =
  23. 23.542 − 255 =
  24. 24.158 + 324 =
  25. 25.621 + 568 =
  26. 26.437 − 275 =
  27. 27.249 + 251 =
  28. 28.431 − 242 =
  29. 29.183 + 291 =
  30. 30.781 − 132 =
  31. 31.354 + 347 =
  32. 32.288 + 474 =
  33. 33.468 − 238 =
  34. 34.653 − 127 =
  35. 35.697 − 483 =
  36. 36.582 − 318 =
  37. 37.362 + 274 =
  38. 38.141 + 629 =
  39. 39.806 − 587 =
  40. 40.223 + 604 =

Answer key

  1. 1000
  2. 1162
  3. 420
  4. 1160
  5. 1081
  6. 132
  7. 661
  8. 648
  9. 842
  10. 625
  11. 878
  12. 484
  13. 861
  14. 170
  15. 811
  16. 1188
  17. 483
  18. 137
  19. 259
  20. 1002
  21. 845
  22. 293
  23. 287
  24. 482
  25. 1189
  26. 162
  27. 500
  28. 189
  29. 474
  30. 649
  31. 701
  32. 762
  33. 230
  34. 526
  35. 214
  36. 264
  37. 636
  38. 770
  39. 219
  40. 827

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