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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 158 · 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. 1.607 + 273 =
  2. 2.533 + 125 =
  3. 3.678 + 256 =
  4. 4.493 − 205 =
  5. 5.618 − 154 =
  6. 6.205 + 361 =
  7. 7.984 − 707 =
  8. 8.329 + 611 =
  9. 9.547 − 184 =
  10. 10.648 + 632 =
  11. 11.729 − 366 =
  12. 12.381 + 163 =
  13. 13.718 + 439 =
  14. 14.290 + 551 =
  15. 15.205 + 337 =
  16. 16.694 − 233 =
  17. 17.738 − 172 =
  18. 18.610 − 126 =
  19. 19.424 − 217 =
  20. 20.191 + 262 =
  21. 21.207 + 404 =
  22. 22.473 − 215 =
  23. 23.612 + 446 =
  24. 24.819 − 257 =
  25. 25.150 + 191 =
  26. 26.123 + 563 =
  27. 27.356 + 499 =
  28. 28.290 + 371 =
  29. 29.463 − 237 =
  30. 30.672 − 321 =
  31. 31.851 − 282 =
  32. 32.380 + 453 =
  33. 33.695 + 546 =
  34. 34.614 − 512 =
  35. 35.495 + 511 =
  36. 36.335 + 271 =
  37. 37.418 − 213 =
  38. 38.763 − 126 =
  39. 39.440 − 309 =
  40. 40.222 + 189 =

Answer key

  1. 880
  2. 658
  3. 934
  4. 288
  5. 464
  6. 566
  7. 277
  8. 940
  9. 363
  10. 1280
  11. 363
  12. 544
  13. 1157
  14. 841
  15. 542
  16. 461
  17. 566
  18. 484
  19. 207
  20. 453
  21. 611
  22. 258
  23. 1058
  24. 562
  25. 341
  26. 686
  27. 855
  28. 661
  29. 226
  30. 351
  31. 569
  32. 833
  33. 1241
  34. 102
  35. 1006
  36. 606
  37. 205
  38. 637
  39. 131
  40. 411

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