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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 514 · 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. 1.660 + 244 =
  2. 2.193 + 561 =
  3. 3.146 + 513 =
  4. 4.143 + 531 =
  5. 5.554 + 385 =
  6. 6.654 + 344 =
  7. 7.466 + 461 =
  8. 8.625 + 687 =
  9. 9.799 − 665 =
  10. 10.486 + 147 =
  11. 11.822 − 133 =
  12. 12.675 + 187 =
  13. 13.182 + 291 =
  14. 14.160 + 684 =
  15. 15.355 + 554 =
  16. 16.831 − 486 =
  17. 17.463 + 666 =
  18. 18.235 + 248 =
  19. 19.832 − 275 =
  20. 20.670 + 509 =
  21. 21.480 + 381 =
  22. 22.389 + 464 =
  23. 23.207 + 265 =
  24. 24.429 + 133 =
  25. 25.520 − 188 =
  26. 26.739 − 521 =
  27. 27.381 + 464 =
  28. 28.864 − 473 =
  29. 29.286 + 369 =
  30. 30.738 − 159 =
  31. 31.612 − 448 =
  32. 32.570 + 628 =
  33. 33.811 − 435 =
  34. 34.167 + 656 =
  35. 35.591 + 571 =
  36. 36.658 + 205 =
  37. 37.441 − 173 =
  38. 38.464 − 154 =
  39. 39.431 − 282 =
  40. 40.764 + 358 =

Answer key

  1. 904
  2. 754
  3. 659
  4. 674
  5. 939
  6. 998
  7. 927
  8. 1312
  9. 134
  10. 633
  11. 689
  12. 862
  13. 473
  14. 844
  15. 909
  16. 345
  17. 1129
  18. 483
  19. 557
  20. 1179
  21. 861
  22. 853
  23. 472
  24. 562
  25. 332
  26. 218
  27. 845
  28. 391
  29. 655
  30. 579
  31. 164
  32. 1198
  33. 376
  34. 823
  35. 1162
  36. 863
  37. 268
  38. 310
  39. 149
  40. 1122

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