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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 163 · 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. 1.714 − 369 =
  2. 2.643 − 168 =
  3. 3.303 + 611 =
  4. 4.236 + 539 =
  5. 5.424 − 236 =
  6. 6.637 + 216 =
  7. 7.783 − 184 =
  8. 8.595 + 651 =
  9. 9.561 + 188 =
  10. 10.667 + 581 =
  11. 11.270 + 682 =
  12. 12.164 + 244 =
  13. 13.697 − 176 =
  14. 14.670 + 552 =
  15. 15.558 + 331 =
  16. 16.212 + 395 =
  17. 17.529 − 238 =
  18. 18.486 + 598 =
  19. 19.512 + 346 =
  20. 20.723 + 637 =
  21. 21.468 − 226 =
  22. 22.481 − 246 =
  23. 23.134 + 151 =
  24. 24.523 + 211 =
  25. 25.495 − 328 =
  26. 26.573 + 301 =
  27. 27.749 + 493 =
  28. 28.651 − 318 =
  29. 29.636 + 136 =
  30. 30.593 − 131 =
  31. 31.588 − 297 =
  32. 32.985 − 772 =
  33. 33.746 − 179 =
  34. 34.482 + 254 =
  35. 35.132 + 621 =
  36. 36.619 − 149 =
  37. 37.589 + 501 =
  38. 38.417 + 218 =
  39. 39.775 − 427 =
  40. 40.775 + 354 =

Answer key

  1. 345
  2. 475
  3. 914
  4. 775
  5. 188
  6. 853
  7. 599
  8. 1246
  9. 749
  10. 1248
  11. 952
  12. 408
  13. 521
  14. 1222
  15. 889
  16. 607
  17. 291
  18. 1084
  19. 858
  20. 1360
  21. 242
  22. 235
  23. 285
  24. 734
  25. 167
  26. 874
  27. 1242
  28. 333
  29. 772
  30. 462
  31. 291
  32. 213
  33. 567
  34. 736
  35. 753
  36. 470
  37. 1090
  38. 635
  39. 348
  40. 1129

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