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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 957 · 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. 1.610 − 372 =
  2. 2.472 − 151 =
  3. 3.439 + 619 =
  4. 4.148 + 541 =
  5. 5.678 − 296 =
  6. 6.426 − 136 =
  7. 7.753 + 311 =
  8. 8.936 − 266 =
  9. 9.745 + 664 =
  10. 10.129 + 202 =
  11. 11.699 + 603 =
  12. 12.137 + 573 =
  13. 13.506 + 398 =
  14. 14.646 − 376 =
  15. 15.486 − 299 =
  16. 16.213 + 153 =
  17. 17.916 − 432 =
  18. 18.662 + 661 =
  19. 19.470 − 125 =
  20. 20.420 − 194 =
  21. 21.639 + 196 =
  22. 22.698 − 213 =
  23. 23.946 − 219 =
  24. 24.888 − 471 =
  25. 25.780 + 667 =
  26. 26.557 − 347 =
  27. 27.442 + 525 =
  28. 28.788 + 582 =
  29. 29.174 + 337 =
  30. 30.874 − 405 =
  31. 31.587 − 292 =
  32. 32.897 − 121 =
  33. 33.741 + 621 =
  34. 34.317 + 587 =
  35. 35.776 − 483 =
  36. 36.715 + 179 =
  37. 37.744 − 357 =
  38. 38.975 − 392 =
  39. 39.128 + 195 =
  40. 40.546 + 613 =

Answer key

  1. 238
  2. 321
  3. 1058
  4. 689
  5. 382
  6. 290
  7. 1064
  8. 670
  9. 1409
  10. 331
  11. 1302
  12. 710
  13. 904
  14. 270
  15. 187
  16. 366
  17. 484
  18. 1323
  19. 345
  20. 226
  21. 835
  22. 485
  23. 727
  24. 417
  25. 1447
  26. 210
  27. 967
  28. 1370
  29. 511
  30. 469
  31. 295
  32. 776
  33. 1362
  34. 904
  35. 293
  36. 894
  37. 387
  38. 583
  39. 323
  40. 1159

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