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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 525 · 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. 1.216 + 374 =
  2. 2.609 − 413 =
  3. 3.914 − 114 =
  4. 4.901 − 571 =
  5. 5.754 − 342 =
  6. 6.885 − 131 =
  7. 7.622 − 341 =
  8. 8.809 − 535 =
  9. 9.383 + 675 =
  10. 10.410 + 191 =
  11. 11.210 + 389 =
  12. 12.272 + 681 =
  13. 13.466 + 215 =
  14. 14.339 + 262 =
  15. 15.146 + 568 =
  16. 16.970 − 129 =
  17. 17.846 − 249 =
  18. 18.552 − 376 =
  19. 19.552 − 134 =
  20. 20.675 − 438 =
  21. 21.681 − 223 =
  22. 22.302 + 453 =
  23. 23.570 − 403 =
  24. 24.787 + 336 =
  25. 25.500 + 631 =
  26. 26.140 + 478 =
  27. 27.887 − 237 =
  28. 28.830 − 367 =
  29. 29.190 + 401 =
  30. 30.412 − 261 =
  31. 31.454 − 271 =
  32. 32.527 + 504 =
  33. 33.899 − 201 =
  34. 34.712 + 161 =
  35. 35.869 − 694 =
  36. 36.208 + 561 =
  37. 37.688 + 188 =
  38. 38.770 − 335 =
  39. 39.968 − 772 =
  40. 40.469 + 143 =

Answer key

  1. 590
  2. 196
  3. 800
  4. 330
  5. 412
  6. 754
  7. 281
  8. 274
  9. 1058
  10. 601
  11. 599
  12. 953
  13. 681
  14. 601
  15. 714
  16. 841
  17. 597
  18. 176
  19. 418
  20. 237
  21. 458
  22. 755
  23. 167
  24. 1123
  25. 1131
  26. 618
  27. 650
  28. 463
  29. 591
  30. 151
  31. 183
  32. 1031
  33. 698
  34. 873
  35. 175
  36. 769
  37. 876
  38. 435
  39. 196
  40. 612

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