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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 815 · 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. 1.525 − 211 =
  2. 2.536 + 126 =
  3. 3.554 − 301 =
  4. 4.952 − 747 =
  5. 5.421 − 126 =
  6. 6.219 + 394 =
  7. 7.249 + 457 =
  8. 8.647 + 141 =
  9. 9.377 + 125 =
  10. 10.237 + 121 =
  11. 11.365 + 645 =
  12. 12.508 − 301 =
  13. 13.437 − 269 =
  14. 14.599 + 339 =
  15. 15.417 + 619 =
  16. 16.938 − 782 =
  17. 17.962 − 796 =
  18. 18.510 + 673 =
  19. 19.718 + 218 =
  20. 20.573 + 346 =
  21. 21.436 + 141 =
  22. 22.273 + 226 =
  23. 23.541 − 397 =
  24. 24.213 + 565 =
  25. 25.156 + 176 =
  26. 26.259 + 676 =
  27. 27.430 − 303 =
  28. 28.611 + 405 =
  29. 29.537 + 159 =
  30. 30.923 − 186 =
  31. 31.522 − 408 =
  32. 32.185 + 661 =
  33. 33.291 + 242 =
  34. 34.760 − 458 =
  35. 35.869 − 189 =
  36. 36.303 + 354 =
  37. 37.872 − 133 =
  38. 38.210 + 281 =
  39. 39.506 − 258 =
  40. 40.558 − 395 =

Answer key

  1. 314
  2. 662
  3. 253
  4. 205
  5. 295
  6. 613
  7. 706
  8. 788
  9. 502
  10. 358
  11. 1010
  12. 207
  13. 168
  14. 938
  15. 1036
  16. 156
  17. 166
  18. 1183
  19. 936
  20. 919
  21. 577
  22. 499
  23. 144
  24. 778
  25. 332
  26. 935
  27. 127
  28. 1016
  29. 696
  30. 737
  31. 114
  32. 846
  33. 533
  34. 302
  35. 680
  36. 657
  37. 739
  38. 491
  39. 248
  40. 163

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