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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 335 · 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. 1.452 − 163 =
  2. 2.423 + 521 =
  3. 3.570 + 148 =
  4. 4.770 − 307 =
  5. 5.636 + 475 =
  6. 6.325 + 211 =
  7. 7.890 − 261 =
  8. 8.209 + 279 =
  9. 9.902 − 431 =
  10. 10.845 − 289 =
  11. 11.554 + 457 =
  12. 12.955 − 562 =
  13. 13.780 − 536 =
  14. 14.609 − 474 =
  15. 15.624 + 673 =
  16. 16.125 + 499 =
  17. 17.604 − 179 =
  18. 18.765 − 571 =
  19. 19.223 + 615 =
  20. 20.511 + 169 =
  21. 21.336 + 574 =
  22. 22.747 − 576 =
  23. 23.603 + 483 =
  24. 24.480 − 314 =
  25. 25.852 − 728 =
  26. 26.853 − 481 =
  27. 27.690 − 422 =
  28. 28.552 − 243 =
  29. 29.414 − 124 =
  30. 30.539 − 143 =
  31. 31.440 + 201 =
  32. 32.756 + 181 =
  33. 33.270 + 265 =
  34. 34.151 + 571 =
  35. 35.285 + 228 =
  36. 36.587 − 187 =
  37. 37.331 + 255 =
  38. 38.322 + 172 =
  39. 39.462 − 253 =
  40. 40.523 − 218 =

Answer key

  1. 289
  2. 944
  3. 718
  4. 463
  5. 1111
  6. 536
  7. 629
  8. 488
  9. 471
  10. 556
  11. 1011
  12. 393
  13. 244
  14. 135
  15. 1297
  16. 624
  17. 425
  18. 194
  19. 838
  20. 680
  21. 910
  22. 171
  23. 1086
  24. 166
  25. 124
  26. 372
  27. 268
  28. 309
  29. 290
  30. 396
  31. 641
  32. 937
  33. 535
  34. 722
  35. 513
  36. 400
  37. 586
  38. 494
  39. 209
  40. 305

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