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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 967 · 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. 1.239 + 561 =
  2. 2.469 + 656 =
  3. 3.942 − 192 =
  4. 4.417 − 188 =
  5. 5.850 − 512 =
  6. 6.724 + 367 =
  7. 7.459 − 203 =
  8. 8.479 − 231 =
  9. 9.897 − 759 =
  10. 10.724 − 174 =
  11. 11.752 − 568 =
  12. 12.902 − 652 =
  13. 13.495 + 632 =
  14. 14.261 + 224 =
  15. 15.314 + 457 =
  16. 16.394 + 376 =
  17. 17.466 + 372 =
  18. 18.456 − 294 =
  19. 19.603 + 509 =
  20. 20.649 + 134 =
  21. 21.541 − 191 =
  22. 22.698 − 545 =
  23. 23.287 + 521 =
  24. 24.656 − 195 =
  25. 25.245 + 224 =
  26. 26.525 − 148 =
  27. 27.847 − 193 =
  28. 28.824 − 352 =
  29. 29.281 + 685 =
  30. 30.481 − 341 =
  31. 31.857 − 356 =
  32. 32.472 − 314 =
  33. 33.434 − 148 =
  34. 34.463 + 658 =
  35. 35.474 + 163 =
  36. 36.470 − 254 =
  37. 37.753 − 191 =
  38. 38.191 + 182 =
  39. 39.894 − 573 =
  40. 40.279 + 285 =

Answer key

  1. 800
  2. 1125
  3. 750
  4. 229
  5. 338
  6. 1091
  7. 256
  8. 248
  9. 138
  10. 550
  11. 184
  12. 250
  13. 1127
  14. 485
  15. 771
  16. 770
  17. 838
  18. 162
  19. 1112
  20. 783
  21. 350
  22. 153
  23. 808
  24. 461
  25. 469
  26. 377
  27. 654
  28. 472
  29. 966
  30. 140
  31. 501
  32. 158
  33. 286
  34. 1121
  35. 637
  36. 216
  37. 562
  38. 373
  39. 321
  40. 564

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