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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 155 · 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. 1.816 − 267 =
  2. 2.776 + 381 =
  3. 3.454 − 323 =
  4. 4.332 + 422 =
  5. 5.723 − 183 =
  6. 6.620 + 621 =
  7. 7.720 + 528 =
  8. 8.132 + 661 =
  9. 9.559 − 286 =
  10. 10.248 + 242 =
  11. 11.662 − 302 =
  12. 12.475 + 595 =
  13. 13.917 − 598 =
  14. 14.192 + 499 =
  15. 15.772 + 181 =
  16. 16.653 + 197 =
  17. 17.466 + 479 =
  18. 18.612 − 208 =
  19. 19.909 − 301 =
  20. 20.587 + 442 =
  21. 21.673 + 311 =
  22. 22.509 + 118 =
  23. 23.782 − 323 =
  24. 24.496 − 388 =
  25. 25.378 + 648 =
  26. 26.581 + 276 =
  27. 27.451 − 295 =
  28. 28.961 − 855 =
  29. 29.967 − 811 =
  30. 30.295 + 616 =
  31. 31.441 − 236 =
  32. 32.601 + 585 =
  33. 33.414 − 212 =
  34. 34.558 + 114 =
  35. 35.654 − 174 =
  36. 36.180 + 651 =
  37. 37.702 + 123 =
  38. 38.767 + 459 =
  39. 39.754 − 639 =
  40. 40.416 + 137 =

Answer key

  1. 549
  2. 1157
  3. 131
  4. 754
  5. 540
  6. 1241
  7. 1248
  8. 793
  9. 273
  10. 490
  11. 360
  12. 1070
  13. 319
  14. 691
  15. 953
  16. 850
  17. 945
  18. 404
  19. 608
  20. 1029
  21. 984
  22. 627
  23. 459
  24. 108
  25. 1026
  26. 857
  27. 156
  28. 106
  29. 156
  30. 911
  31. 205
  32. 1186
  33. 202
  34. 672
  35. 480
  36. 831
  37. 825
  38. 1226
  39. 115
  40. 553

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