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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 106 · 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. 1.516 − 319 =
  2. 2.525 − 271 =
  3. 3.589 − 381 =
  4. 4.466 − 195 =
  5. 5.666 − 263 =
  6. 6.806 − 174 =
  7. 7.558 + 114 =
  8. 8.276 + 641 =
  9. 9.748 + 243 =
  10. 10.220 + 222 =
  11. 11.898 − 581 =
  12. 12.773 + 561 =
  13. 13.969 − 186 =
  14. 14.754 − 214 =
  15. 15.765 − 444 =
  16. 16.310 + 315 =
  17. 17.659 − 335 =
  18. 18.194 + 621 =
  19. 19.341 + 499 =
  20. 20.531 − 133 =
  21. 21.646 + 306 =
  22. 22.365 + 625 =
  23. 23.480 − 298 =
  24. 24.710 + 177 =
  25. 25.214 + 306 =
  26. 26.972 − 549 =
  27. 27.439 − 203 =
  28. 28.552 + 135 =
  29. 29.753 + 577 =
  30. 30.624 − 503 =
  31. 31.707 − 314 =
  32. 32.138 + 601 =
  33. 33.664 + 393 =
  34. 34.531 − 355 =
  35. 35.483 + 283 =
  36. 36.334 + 419 =
  37. 37.789 + 366 =
  38. 38.510 − 289 =
  39. 39.581 − 441 =
  40. 40.489 + 619 =

Answer key

  1. 197
  2. 254
  3. 208
  4. 271
  5. 403
  6. 632
  7. 672
  8. 917
  9. 991
  10. 442
  11. 317
  12. 1334
  13. 783
  14. 540
  15. 321
  16. 625
  17. 324
  18. 815
  19. 840
  20. 398
  21. 952
  22. 990
  23. 182
  24. 887
  25. 520
  26. 423
  27. 236
  28. 687
  29. 1330
  30. 121
  31. 393
  32. 739
  33. 1057
  34. 176
  35. 766
  36. 753
  37. 1155
  38. 221
  39. 140
  40. 1108

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