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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 943 · 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. 1.505 − 399 =
  2. 2.540 + 161 =
  3. 3.214 + 383 =
  4. 4.424 + 277 =
  5. 5.568 + 229 =
  6. 6.457 + 479 =
  7. 7.362 + 602 =
  8. 8.680 − 444 =
  9. 9.659 − 171 =
  10. 10.662 − 216 =
  11. 11.951 − 647 =
  12. 12.189 + 547 =
  13. 13.500 + 625 =
  14. 14.486 + 202 =
  15. 15.356 + 541 =
  16. 16.487 + 548 =
  17. 17.789 − 256 =
  18. 18.747 + 168 =
  19. 19.640 − 184 =
  20. 20.645 + 207 =
  21. 21.788 − 561 =
  22. 22.249 + 414 =
  23. 23.313 + 367 =
  24. 24.429 + 228 =
  25. 25.376 + 398 =
  26. 26.133 + 127 =
  27. 27.945 − 228 =
  28. 28.536 − 306 =
  29. 29.518 − 357 =
  30. 30.988 − 609 =
  31. 31.132 + 298 =
  32. 32.266 + 268 =
  33. 33.757 − 231 =
  34. 34.288 + 554 =
  35. 35.371 + 511 =
  36. 36.521 + 391 =
  37. 37.218 + 555 =
  38. 38.505 + 371 =
  39. 39.421 + 142 =
  40. 40.727 − 291 =

Answer key

  1. 106
  2. 701
  3. 597
  4. 701
  5. 797
  6. 936
  7. 964
  8. 236
  9. 488
  10. 446
  11. 304
  12. 736
  13. 1125
  14. 688
  15. 897
  16. 1035
  17. 533
  18. 915
  19. 456
  20. 852
  21. 227
  22. 663
  23. 680
  24. 657
  25. 774
  26. 260
  27. 717
  28. 230
  29. 161
  30. 379
  31. 430
  32. 534
  33. 526
  34. 842
  35. 882
  36. 912
  37. 773
  38. 876
  39. 563
  40. 436

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