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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 14 · 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. 1.599 + 231 =
  2. 2.563 − 257 =
  3. 3.467 − 164 =
  4. 4.530 + 684 =
  5. 5.176 + 655 =
  6. 6.761 + 264 =
  7. 7.775 − 379 =
  8. 8.318 + 193 =
  9. 9.725 + 216 =
  10. 10.319 + 663 =
  11. 11.202 + 491 =
  12. 12.434 − 285 =
  13. 13.480 − 249 =
  14. 14.205 + 477 =
  15. 15.233 + 161 =
  16. 16.754 + 426 =
  17. 17.255 + 249 =
  18. 18.137 + 642 =
  19. 19.656 − 249 =
  20. 20.467 + 342 =
  21. 21.588 + 149 =
  22. 22.180 + 113 =
  23. 23.274 + 128 =
  24. 24.945 − 834 =
  25. 25.560 − 315 =
  26. 26.495 − 126 =
  27. 27.548 − 396 =
  28. 28.396 + 399 =
  29. 29.485 − 199 =
  30. 30.572 − 306 =
  31. 31.197 + 301 =
  32. 32.524 − 298 =
  33. 33.829 − 556 =
  34. 34.431 − 121 =
  35. 35.473 + 176 =
  36. 36.858 − 208 =
  37. 37.250 + 349 =
  38. 38.553 − 269 =
  39. 39.330 + 621 =
  40. 40.465 + 632 =

Answer key

  1. 830
  2. 306
  3. 303
  4. 1214
  5. 831
  6. 1025
  7. 396
  8. 511
  9. 941
  10. 982
  11. 693
  12. 149
  13. 231
  14. 682
  15. 394
  16. 1180
  17. 504
  18. 779
  19. 407
  20. 809
  21. 737
  22. 293
  23. 402
  24. 111
  25. 245
  26. 369
  27. 152
  28. 795
  29. 286
  30. 266
  31. 498
  32. 226
  33. 273
  34. 310
  35. 649
  36. 650
  37. 599
  38. 284
  39. 951
  40. 1097

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