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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 848 · 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. 1.969 − 249 =
  2. 2.295 + 173 =
  3. 3.940 − 149 =
  4. 4.817 − 309 =
  5. 5.135 + 353 =
  6. 6.541 − 141 =
  7. 7.566 + 128 =
  8. 8.660 + 115 =
  9. 9.506 − 197 =
  10. 10.686 − 301 =
  11. 11.223 + 543 =
  12. 12.712 + 293 =
  13. 13.939 − 506 =
  14. 14.712 + 235 =
  15. 15.922 − 277 =
  16. 16.747 + 472 =
  17. 17.132 + 168 =
  18. 18.500 − 357 =
  19. 19.293 + 468 =
  20. 20.232 + 476 =
  21. 21.541 + 673 =
  22. 22.675 + 251 =
  23. 23.225 + 557 =
  24. 24.591 + 611 =
  25. 25.359 + 655 =
  26. 26.142 + 648 =
  27. 27.213 + 192 =
  28. 28.351 + 165 =
  29. 29.464 + 311 =
  30. 30.593 − 117 =
  31. 31.521 − 305 =
  32. 32.908 − 431 =
  33. 33.253 + 635 =
  34. 34.519 − 195 =
  35. 35.758 − 144 =
  36. 36.504 + 441 =
  37. 37.648 + 568 =
  38. 38.435 − 318 =
  39. 39.709 + 418 =
  40. 40.786 − 666 =

Answer key

  1. 720
  2. 468
  3. 791
  4. 508
  5. 488
  6. 400
  7. 694
  8. 775
  9. 309
  10. 385
  11. 766
  12. 1005
  13. 433
  14. 947
  15. 645
  16. 1219
  17. 300
  18. 143
  19. 761
  20. 708
  21. 1214
  22. 926
  23. 782
  24. 1202
  25. 1014
  26. 790
  27. 405
  28. 516
  29. 775
  30. 476
  31. 216
  32. 477
  33. 888
  34. 324
  35. 614
  36. 945
  37. 1216
  38. 117
  39. 1127
  40. 120

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