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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 231 · 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. 1.490 − 353 =
  2. 2.662 − 281 =
  3. 3.479 + 377 =
  4. 4.256 + 174 =
  5. 5.246 + 404 =
  6. 6.129 + 165 =
  7. 7.771 − 475 =
  8. 8.155 + 369 =
  9. 9.903 − 669 =
  10. 10.804 − 543 =
  11. 11.337 + 664 =
  12. 12.741 − 161 =
  13. 13.730 − 346 =
  14. 14.678 − 343 =
  15. 15.465 − 281 =
  16. 16.220 + 122 =
  17. 17.784 − 267 =
  18. 18.972 − 349 =
  19. 19.389 + 682 =
  20. 20.423 − 161 =
  21. 21.195 + 175 =
  22. 22.891 − 541 =
  23. 23.617 − 512 =
  24. 24.238 + 506 =
  25. 25.727 − 186 =
  26. 26.186 + 223 =
  27. 27.705 − 543 =
  28. 28.697 + 293 =
  29. 29.249 + 612 =
  30. 30.245 + 248 =
  31. 31.295 + 236 =
  32. 32.135 + 254 =
  33. 33.132 + 241 =
  34. 34.500 + 499 =
  35. 35.339 + 511 =
  36. 36.338 + 602 =
  37. 37.656 + 554 =
  38. 38.435 + 543 =
  39. 39.761 + 203 =
  40. 40.816 − 513 =

Answer key

  1. 137
  2. 381
  3. 856
  4. 430
  5. 650
  6. 294
  7. 296
  8. 524
  9. 234
  10. 261
  11. 1001
  12. 580
  13. 384
  14. 335
  15. 184
  16. 342
  17. 517
  18. 623
  19. 1071
  20. 262
  21. 370
  22. 350
  23. 105
  24. 744
  25. 541
  26. 409
  27. 162
  28. 990
  29. 861
  30. 493
  31. 531
  32. 389
  33. 373
  34. 999
  35. 850
  36. 940
  37. 1210
  38. 978
  39. 964
  40. 303

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