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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 243 · 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. 1.754 + 516 =
  2. 2.153 + 501 =
  3. 3.831 − 651 =
  4. 4.316 + 431 =
  5. 5.777 − 617 =
  6. 6.430 − 146 =
  7. 7.978 − 289 =
  8. 8.306 + 443 =
  9. 9.126 + 651 =
  10. 10.409 + 631 =
  11. 11.911 − 358 =
  12. 12.649 + 641 =
  13. 13.552 + 642 =
  14. 14.641 − 361 =
  15. 15.736 − 223 =
  16. 16.462 − 184 =
  17. 17.208 + 369 =
  18. 18.829 − 441 =
  19. 19.625 + 401 =
  20. 20.804 − 701 =
  21. 21.505 + 395 =
  22. 22.434 − 173 =
  23. 23.162 + 676 =
  24. 24.740 − 219 =
  25. 25.512 + 594 =
  26. 26.550 − 377 =
  27. 27.620 + 662 =
  28. 28.819 − 585 =
  29. 29.945 − 772 =
  30. 30.852 − 271 =
  31. 31.857 − 678 =
  32. 32.967 − 155 =
  33. 33.390 + 648 =
  34. 34.879 − 232 =
  35. 35.432 − 239 =
  36. 36.206 + 254 =
  37. 37.563 + 133 =
  38. 38.582 + 331 =
  39. 39.415 + 468 =
  40. 40.482 + 573 =

Answer key

  1. 1270
  2. 654
  3. 180
  4. 747
  5. 160
  6. 284
  7. 689
  8. 749
  9. 777
  10. 1040
  11. 553
  12. 1290
  13. 1194
  14. 280
  15. 513
  16. 278
  17. 577
  18. 388
  19. 1026
  20. 103
  21. 900
  22. 261
  23. 838
  24. 521
  25. 1106
  26. 173
  27. 1282
  28. 234
  29. 173
  30. 581
  31. 179
  32. 812
  33. 1038
  34. 647
  35. 193
  36. 460
  37. 696
  38. 913
  39. 883
  40. 1055

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