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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 539 · 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. 1.459 − 186 =
  2. 2.278 + 202 =
  3. 3.425 − 139 =
  4. 4.166 + 344 =
  5. 5.470 − 318 =
  6. 6.907 − 481 =
  7. 7.665 − 298 =
  8. 8.467 + 184 =
  9. 9.709 + 651 =
  10. 10.243 + 127 =
  11. 11.131 + 122 =
  12. 12.831 − 243 =
  13. 13.162 + 621 =
  14. 14.776 + 567 =
  15. 15.887 − 244 =
  16. 16.443 + 208 =
  17. 17.454 + 157 =
  18. 18.582 − 253 =
  19. 19.283 + 539 =
  20. 20.240 + 366 =
  21. 21.661 + 541 =
  22. 22.599 − 122 =
  23. 23.156 + 634 =
  24. 24.618 + 576 =
  25. 25.559 − 223 =
  26. 26.523 + 603 =
  27. 27.690 − 161 =
  28. 28.598 + 179 =
  29. 29.473 + 511 =
  30. 30.236 + 251 =
  31. 31.149 + 386 =
  32. 32.647 − 532 =
  33. 33.128 + 184 =
  34. 34.982 − 285 =
  35. 35.760 + 441 =
  36. 36.546 − 149 =
  37. 37.729 + 488 =
  38. 38.380 + 408 =
  39. 39.599 + 675 =
  40. 40.511 + 515 =

Answer key

  1. 273
  2. 480
  3. 286
  4. 510
  5. 152
  6. 426
  7. 367
  8. 651
  9. 1360
  10. 370
  11. 253
  12. 588
  13. 783
  14. 1343
  15. 643
  16. 651
  17. 611
  18. 329
  19. 822
  20. 606
  21. 1202
  22. 477
  23. 790
  24. 1194
  25. 336
  26. 1126
  27. 529
  28. 777
  29. 984
  30. 487
  31. 535
  32. 115
  33. 312
  34. 697
  35. 1201
  36. 397
  37. 1217
  38. 788
  39. 1274
  40. 1026

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