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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 446 · 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. 1.685 − 431 =
  2. 2.390 + 524 =
  3. 3.629 − 448 =
  4. 4.770 + 196 =
  5. 5.695 + 452 =
  6. 6.546 + 603 =
  7. 7.156 + 657 =
  8. 8.466 + 191 =
  9. 9.530 + 452 =
  10. 10.867 − 667 =
  11. 11.758 − 511 =
  12. 12.895 − 129 =
  13. 13.357 + 521 =
  14. 14.423 − 182 =
  15. 15.763 + 554 =
  16. 16.770 − 347 =
  17. 17.487 − 205 =
  18. 18.466 + 378 =
  19. 19.679 − 466 =
  20. 20.750 + 149 =
  21. 21.311 + 581 =
  22. 22.305 + 241 =
  23. 23.365 + 586 =
  24. 24.502 + 333 =
  25. 25.567 + 612 =
  26. 26.808 − 122 =
  27. 27.426 + 611 =
  28. 28.690 − 224 =
  29. 29.571 − 309 =
  30. 30.355 + 246 =
  31. 31.138 + 238 =
  32. 32.498 + 511 =
  33. 33.594 − 379 =
  34. 34.350 + 677 =
  35. 35.299 + 497 =
  36. 36.902 − 149 =
  37. 37.133 + 137 =
  38. 38.584 + 424 =
  39. 39.605 + 311 =
  40. 40.675 + 535 =

Answer key

  1. 254
  2. 914
  3. 181
  4. 966
  5. 1147
  6. 1149
  7. 813
  8. 657
  9. 982
  10. 200
  11. 247
  12. 766
  13. 878
  14. 241
  15. 1317
  16. 423
  17. 282
  18. 844
  19. 213
  20. 899
  21. 892
  22. 546
  23. 951
  24. 835
  25. 1179
  26. 686
  27. 1037
  28. 466
  29. 262
  30. 601
  31. 376
  32. 1009
  33. 215
  34. 1027
  35. 796
  36. 753
  37. 270
  38. 1008
  39. 916
  40. 1210

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