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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 211 · 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. 1.437 − 178 =
  2. 2.858 − 318 =
  3. 3.750 + 538 =
  4. 4.742 + 629 =
  5. 5.773 − 412 =
  6. 6.473 − 227 =
  7. 7.573 + 655 =
  8. 8.699 + 421 =
  9. 9.329 + 301 =
  10. 10.509 − 185 =
  11. 11.678 + 178 =
  12. 12.471 + 689 =
  13. 13.283 + 539 =
  14. 14.131 + 327 =
  15. 15.529 + 316 =
  16. 16.634 − 157 =
  17. 17.594 + 662 =
  18. 18.251 + 471 =
  19. 19.644 + 241 =
  20. 20.961 − 487 =
  21. 21.657 + 487 =
  22. 22.417 − 183 =
  23. 23.543 + 541 =
  24. 24.714 − 254 =
  25. 25.313 + 403 =
  26. 26.831 − 241 =
  27. 27.698 + 307 =
  28. 28.265 + 112 =
  29. 29.781 + 215 =
  30. 30.788 + 534 =
  31. 31.814 − 153 =
  32. 32.574 − 388 =
  33. 33.485 − 321 =
  34. 34.404 + 421 =
  35. 35.543 − 339 =
  36. 36.544 − 231 =
  37. 37.569 − 337 =
  38. 38.716 + 618 =
  39. 39.757 − 509 =
  40. 40.126 + 371 =

Answer key

  1. 259
  2. 540
  3. 1288
  4. 1371
  5. 361
  6. 246
  7. 1228
  8. 1120
  9. 630
  10. 324
  11. 856
  12. 1160
  13. 822
  14. 458
  15. 845
  16. 477
  17. 1256
  18. 722
  19. 885
  20. 474
  21. 1144
  22. 234
  23. 1084
  24. 460
  25. 716
  26. 590
  27. 1005
  28. 377
  29. 996
  30. 1322
  31. 661
  32. 186
  33. 164
  34. 825
  35. 204
  36. 313
  37. 232
  38. 1334
  39. 248
  40. 497

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