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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 874 · 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. 1.262 + 298 =
  2. 2.234 + 435 =
  3. 3.855 − 185 =
  4. 4.490 − 155 =
  5. 5.565 − 196 =
  6. 6.522 − 202 =
  7. 7.197 + 683 =
  8. 8.593 + 237 =
  9. 9.540 − 365 =
  10. 10.138 + 471 =
  11. 11.852 − 197 =
  12. 12.849 − 187 =
  13. 13.425 + 515 =
  14. 14.222 + 595 =
  15. 15.492 + 611 =
  16. 16.951 − 114 =
  17. 17.344 + 397 =
  18. 18.173 + 604 =
  19. 19.571 − 439 =
  20. 20.351 + 584 =
  21. 21.606 + 244 =
  22. 22.858 − 676 =
  23. 23.650 + 535 =
  24. 24.545 + 681 =
  25. 25.760 + 239 =
  26. 26.470 − 317 =
  27. 27.643 − 162 =
  28. 28.442 − 199 =
  29. 29.461 − 292 =
  30. 30.775 + 239 =
  31. 31.691 − 329 =
  32. 32.330 + 532 =
  33. 33.913 − 395 =
  34. 34.544 − 173 =
  35. 35.402 + 577 =
  36. 36.725 + 203 =
  37. 37.160 + 596 =
  38. 38.397 + 322 =
  39. 39.655 + 551 =
  40. 40.384 + 229 =

Answer key

  1. 560
  2. 669
  3. 670
  4. 335
  5. 369
  6. 320
  7. 880
  8. 830
  9. 175
  10. 609
  11. 655
  12. 662
  13. 940
  14. 817
  15. 1103
  16. 837
  17. 741
  18. 777
  19. 132
  20. 935
  21. 850
  22. 182
  23. 1185
  24. 1226
  25. 999
  26. 153
  27. 481
  28. 243
  29. 169
  30. 1014
  31. 362
  32. 862
  33. 518
  34. 371
  35. 979
  36. 928
  37. 756
  38. 719
  39. 1206
  40. 613

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