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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 758 · 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. 1.885 − 317 =
  2. 2.621 + 241 =
  3. 3.451 − 231 =
  4. 4.548 + 144 =
  5. 5.660 + 202 =
  6. 6.626 + 485 =
  7. 7.473 − 358 =
  8. 8.846 − 228 =
  9. 9.631 + 336 =
  10. 10.472 − 295 =
  11. 11.234 + 231 =
  12. 12.187 + 561 =
  13. 13.494 + 668 =
  14. 14.422 − 185 =
  15. 15.478 − 196 =
  16. 16.963 − 265 =
  17. 17.983 − 321 =
  18. 18.352 + 191 =
  19. 19.176 + 403 =
  20. 20.727 + 537 =
  21. 21.511 + 455 =
  22. 22.319 + 393 =
  23. 23.266 + 526 =
  24. 24.282 + 171 =
  25. 25.518 − 191 =
  26. 26.281 + 351 =
  27. 27.600 − 126 =
  28. 28.914 − 475 =
  29. 29.138 + 233 =
  30. 30.496 + 564 =
  31. 31.171 + 389 =
  32. 32.637 − 347 =
  33. 33.583 + 363 =
  34. 34.145 + 379 =
  35. 35.655 − 252 =
  36. 36.193 + 642 =
  37. 37.886 − 626 =
  38. 38.486 − 114 =
  39. 39.290 + 152 =
  40. 40.143 + 396 =

Answer key

  1. 568
  2. 862
  3. 220
  4. 692
  5. 862
  6. 1111
  7. 115
  8. 618
  9. 967
  10. 177
  11. 465
  12. 748
  13. 1162
  14. 237
  15. 282
  16. 698
  17. 662
  18. 543
  19. 579
  20. 1264
  21. 966
  22. 712
  23. 792
  24. 453
  25. 327
  26. 632
  27. 474
  28. 439
  29. 371
  30. 1060
  31. 560
  32. 290
  33. 946
  34. 524
  35. 403
  36. 835
  37. 260
  38. 372
  39. 442
  40. 539

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