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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 53 · 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. 1.561 − 229 =
  2. 2.329 + 285 =
  3. 3.385 + 428 =
  4. 4.390 + 214 =
  5. 5.354 + 162 =
  6. 6.569 + 442 =
  7. 7.632 + 426 =
  8. 8.266 + 582 =
  9. 9.764 + 651 =
  10. 10.478 + 582 =
  11. 11.325 + 161 =
  12. 12.323 + 431 =
  13. 13.349 + 225 =
  14. 14.255 + 377 =
  15. 15.564 − 238 =
  16. 16.693 + 339 =
  17. 17.637 − 331 =
  18. 18.876 − 501 =
  19. 19.912 − 156 =
  20. 20.372 + 466 =
  21. 21.284 + 264 =
  22. 22.270 + 231 =
  23. 23.185 + 471 =
  24. 24.668 − 542 =
  25. 25.492 − 295 =
  26. 26.429 − 273 =
  27. 27.451 − 237 =
  28. 28.495 − 321 =
  29. 29.481 + 132 =
  30. 30.264 + 147 =
  31. 31.491 − 195 =
  32. 32.407 + 546 =
  33. 33.350 + 539 =
  34. 34.511 + 291 =
  35. 35.970 − 223 =
  36. 36.556 − 412 =
  37. 37.208 + 595 =
  38. 38.612 + 577 =
  39. 39.357 + 581 =
  40. 40.453 − 204 =

Answer key

  1. 332
  2. 614
  3. 813
  4. 604
  5. 516
  6. 1011
  7. 1058
  8. 848
  9. 1415
  10. 1060
  11. 486
  12. 754
  13. 574
  14. 632
  15. 326
  16. 1032
  17. 306
  18. 375
  19. 756
  20. 838
  21. 548
  22. 501
  23. 656
  24. 126
  25. 197
  26. 156
  27. 214
  28. 174
  29. 613
  30. 411
  31. 296
  32. 953
  33. 889
  34. 802
  35. 747
  36. 144
  37. 803
  38. 1189
  39. 938
  40. 249

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