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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 814 · 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. 1.686 − 205 =
  2. 2.283 + 647 =
  3. 3.445 + 571 =
  4. 4.619 + 407 =
  5. 5.226 + 675 =
  6. 6.757 − 151 =
  7. 7.380 + 389 =
  8. 8.534 − 153 =
  9. 9.960 − 764 =
  10. 10.609 + 161 =
  11. 11.820 − 465 =
  12. 12.366 + 164 =
  13. 13.497 − 356 =
  14. 14.726 − 455 =
  15. 15.744 − 606 =
  16. 16.675 − 554 =
  17. 17.192 + 301 =
  18. 18.585 − 368 =
  19. 19.490 + 243 =
  20. 20.525 − 251 =
  21. 21.154 + 299 =
  22. 22.274 + 179 =
  23. 23.399 + 643 =
  24. 24.841 − 341 =
  25. 25.282 + 272 =
  26. 26.583 + 618 =
  27. 27.589 − 393 =
  28. 28.860 − 212 =
  29. 29.452 − 262 =
  30. 30.544 − 291 =
  31. 31.605 + 257 =
  32. 32.905 − 421 =
  33. 33.972 − 131 =
  34. 34.747 − 128 =
  35. 35.196 + 131 =
  36. 36.563 − 408 =
  37. 37.763 − 361 =
  38. 38.913 − 729 =
  39. 39.689 − 142 =
  40. 40.833 − 347 =

Answer key

  1. 481
  2. 930
  3. 1016
  4. 1026
  5. 901
  6. 606
  7. 769
  8. 381
  9. 196
  10. 770
  11. 355
  12. 530
  13. 141
  14. 271
  15. 138
  16. 121
  17. 493
  18. 217
  19. 733
  20. 274
  21. 453
  22. 453
  23. 1042
  24. 500
  25. 554
  26. 1201
  27. 196
  28. 648
  29. 190
  30. 253
  31. 862
  32. 484
  33. 841
  34. 619
  35. 327
  36. 155
  37. 402
  38. 184
  39. 547
  40. 486

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