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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 619 · 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. 1.450 + 337 =
  2. 2.442 + 441 =
  3. 3.428 + 533 =
  4. 4.612 + 124 =
  5. 5.629 + 324 =
  6. 6.186 + 473 =
  7. 7.546 + 131 =
  8. 8.939 − 451 =
  9. 9.435 − 216 =
  10. 10.736 − 544 =
  11. 11.724 − 615 =
  12. 12.161 + 301 =
  13. 13.614 + 531 =
  14. 14.675 + 185 =
  15. 15.702 + 121 =
  16. 16.830 − 505 =
  17. 17.540 + 641 =
  18. 18.902 − 333 =
  19. 19.587 + 416 =
  20. 20.788 + 453 =
  21. 21.155 + 658 =
  22. 22.674 − 184 =
  23. 23.639 − 483 =
  24. 24.564 + 513 =
  25. 25.145 + 141 =
  26. 26.152 + 481 =
  27. 27.421 + 128 =
  28. 28.545 − 115 =
  29. 29.642 − 141 =
  30. 30.670 − 182 =
  31. 31.467 − 246 =
  32. 32.511 + 302 =
  33. 33.460 − 321 =
  34. 34.602 + 282 =
  35. 35.486 + 388 =
  36. 36.362 + 582 =
  37. 37.304 + 558 =
  38. 38.466 − 334 =
  39. 39.660 + 377 =
  40. 40.169 + 191 =

Answer key

  1. 787
  2. 883
  3. 961
  4. 736
  5. 953
  6. 659
  7. 677
  8. 488
  9. 219
  10. 192
  11. 109
  12. 462
  13. 1145
  14. 860
  15. 823
  16. 325
  17. 1181
  18. 569
  19. 1003
  20. 1241
  21. 813
  22. 490
  23. 156
  24. 1077
  25. 286
  26. 633
  27. 549
  28. 430
  29. 501
  30. 488
  31. 221
  32. 813
  33. 139
  34. 884
  35. 874
  36. 944
  37. 862
  38. 132
  39. 1037
  40. 360

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