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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 742 · 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. 1.477 − 241 =
  2. 2.536 + 268 =
  3. 3.662 + 661 =
  4. 4.481 − 291 =
  5. 5.372 + 382 =
  6. 6.350 + 531 =
  7. 7.309 + 682 =
  8. 8.767 − 253 =
  9. 9.584 − 238 =
  10. 10.453 − 231 =
  11. 11.802 − 345 =
  12. 12.835 − 593 =
  13. 13.311 + 672 =
  14. 14.123 + 141 =
  15. 15.171 + 148 =
  16. 16.493 + 444 =
  17. 17.460 + 556 =
  18. 18.575 + 457 =
  19. 19.934 − 188 =
  20. 20.803 − 148 =
  21. 21.507 − 183 =
  22. 22.472 + 281 =
  23. 23.772 − 302 =
  24. 24.298 + 259 =
  25. 25.245 + 671 =
  26. 26.650 − 434 =
  27. 27.145 + 491 =
  28. 28.333 + 226 =
  29. 29.637 − 274 =
  30. 30.873 − 342 =
  31. 31.551 − 196 =
  32. 32.736 + 353 =
  33. 33.364 + 367 =
  34. 34.627 − 325 =
  35. 35.385 + 663 =
  36. 36.251 + 235 =
  37. 37.854 − 209 =
  38. 38.268 + 459 =
  39. 39.664 + 583 =
  40. 40.702 + 396 =

Answer key

  1. 236
  2. 804
  3. 1323
  4. 190
  5. 754
  6. 881
  7. 991
  8. 514
  9. 346
  10. 222
  11. 457
  12. 242
  13. 983
  14. 264
  15. 319
  16. 937
  17. 1016
  18. 1032
  19. 746
  20. 655
  21. 324
  22. 753
  23. 470
  24. 557
  25. 916
  26. 216
  27. 636
  28. 559
  29. 363
  30. 531
  31. 355
  32. 1089
  33. 731
  34. 302
  35. 1048
  36. 486
  37. 645
  38. 727
  39. 1247
  40. 1098

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