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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 353 · 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. 1.234 + 313 =
  2. 2.955 − 821 =
  3. 3.236 + 231 =
  4. 4.174 + 544 =
  5. 5.609 − 248 =
  6. 6.389 + 155 =
  7. 7.736 − 503 =
  8. 8.235 + 496 =
  9. 9.188 + 654 =
  10. 10.420 − 298 =
  11. 11.322 + 232 =
  12. 12.647 + 321 =
  13. 13.780 − 531 =
  14. 14.206 + 491 =
  15. 15.164 + 441 =
  16. 16.221 + 585 =
  17. 17.570 − 149 =
  18. 18.541 − 181 =
  19. 19.287 + 311 =
  20. 20.254 + 445 =
  21. 21.134 + 251 =
  22. 22.603 − 137 =
  23. 23.477 − 238 =
  24. 24.556 − 329 =
  25. 25.625 − 321 =
  26. 26.965 − 765 =
  27. 27.181 + 322 =
  28. 28.690 + 135 =
  29. 29.412 + 576 =
  30. 30.732 − 581 =
  31. 31.748 + 123 =
  32. 32.477 − 279 =
  33. 33.802 − 684 =
  34. 34.235 + 291 =
  35. 35.172 + 618 =
  36. 36.309 + 176 =
  37. 37.573 − 118 =
  38. 38.473 + 195 =
  39. 39.726 + 402 =
  40. 40.797 − 258 =

Answer key

  1. 547
  2. 134
  3. 467
  4. 718
  5. 361
  6. 544
  7. 233
  8. 731
  9. 842
  10. 122
  11. 554
  12. 968
  13. 249
  14. 697
  15. 605
  16. 806
  17. 421
  18. 360
  19. 598
  20. 699
  21. 385
  22. 466
  23. 239
  24. 227
  25. 304
  26. 200
  27. 503
  28. 825
  29. 988
  30. 151
  31. 871
  32. 198
  33. 118
  34. 526
  35. 790
  36. 485
  37. 455
  38. 668
  39. 1128
  40. 539

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