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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 839 · 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. 1.522 − 286 =
  2. 2.262 + 304 =
  3. 3.482 − 119 =
  4. 4.783 + 332 =
  5. 5.185 + 527 =
  6. 6.474 + 352 =
  7. 7.595 − 259 =
  8. 8.568 − 427 =
  9. 9.744 + 257 =
  10. 10.767 + 418 =
  11. 11.385 + 393 =
  12. 12.868 − 678 =
  13. 13.695 + 283 =
  14. 14.238 + 381 =
  15. 15.292 + 186 =
  16. 16.677 − 493 =
  17. 17.649 + 641 =
  18. 18.510 − 176 =
  19. 19.507 + 144 =
  20. 20.583 − 131 =
  21. 21.657 + 251 =
  22. 22.946 − 131 =
  23. 23.707 − 543 =
  24. 24.912 − 805 =
  25. 25.233 + 584 =
  26. 26.708 − 236 =
  27. 27.389 + 241 =
  28. 28.520 − 203 =
  29. 29.751 + 661 =
  30. 30.743 + 385 =
  31. 31.285 + 686 =
  32. 32.396 + 485 =
  33. 33.618 − 274 =
  34. 34.196 + 586 =
  35. 35.639 + 485 =
  36. 36.865 − 554 =
  37. 37.335 + 665 =
  38. 38.473 + 398 =
  39. 39.442 + 654 =
  40. 40.852 − 528 =

Answer key

  1. 236
  2. 566
  3. 363
  4. 1115
  5. 712
  6. 826
  7. 336
  8. 141
  9. 1001
  10. 1185
  11. 778
  12. 190
  13. 978
  14. 619
  15. 478
  16. 184
  17. 1290
  18. 334
  19. 651
  20. 452
  21. 908
  22. 815
  23. 164
  24. 107
  25. 817
  26. 472
  27. 630
  28. 317
  29. 1412
  30. 1128
  31. 971
  32. 881
  33. 344
  34. 782
  35. 1124
  36. 311
  37. 1000
  38. 871
  39. 1096
  40. 324

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