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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 157 · 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. 1.696 + 254 =
  2. 2.676 + 666 =
  3. 3.453 + 651 =
  4. 4.586 + 174 =
  5. 5.647 + 413 =
  6. 6.947 − 216 =
  7. 7.489 + 361 =
  8. 8.247 + 189 =
  9. 9.321 + 376 =
  10. 10.853 − 631 =
  11. 11.487 − 226 =
  12. 12.744 + 395 =
  13. 13.800 − 289 =
  14. 14.978 − 467 =
  15. 15.891 − 379 =
  16. 16.232 + 146 =
  17. 17.668 + 172 =
  18. 18.858 − 622 =
  19. 19.214 + 678 =
  20. 20.607 − 465 =
  21. 21.690 + 148 =
  22. 22.450 − 142 =
  23. 23.134 + 359 =
  24. 24.231 + 424 =
  25. 25.535 − 381 =
  26. 26.761 + 465 =
  27. 27.259 + 591 =
  28. 28.707 − 136 =
  29. 29.244 + 271 =
  30. 30.129 + 238 =
  31. 31.365 + 328 =
  32. 32.744 − 606 =
  33. 33.418 − 215 =
  34. 34.653 − 472 =
  35. 35.497 + 551 =
  36. 36.663 + 213 =
  37. 37.508 + 615 =
  38. 38.289 + 659 =
  39. 39.728 + 648 =
  40. 40.171 + 309 =

Answer key

  1. 950
  2. 1342
  3. 1104
  4. 760
  5. 1060
  6. 731
  7. 850
  8. 436
  9. 697
  10. 222
  11. 261
  12. 1139
  13. 511
  14. 511
  15. 512
  16. 378
  17. 840
  18. 236
  19. 892
  20. 142
  21. 838
  22. 308
  23. 493
  24. 655
  25. 154
  26. 1226
  27. 850
  28. 571
  29. 515
  30. 367
  31. 693
  32. 138
  33. 203
  34. 181
  35. 1048
  36. 876
  37. 1123
  38. 948
  39. 1376
  40. 480

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