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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 287 · 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. 1.988 − 282 =
  2. 2.292 + 458 =
  3. 3.510 + 608 =
  4. 4.914 − 708 =
  5. 5.950 − 552 =
  6. 6.154 + 419 =
  7. 7.457 − 115 =
  8. 8.488 + 386 =
  9. 9.898 − 737 =
  10. 10.175 + 411 =
  11. 11.769 + 235 =
  12. 12.434 − 214 =
  13. 13.578 + 281 =
  14. 14.719 − 496 =
  15. 15.585 − 455 =
  16. 16.439 + 272 =
  17. 17.246 + 627 =
  18. 18.633 − 162 =
  19. 19.803 − 555 =
  20. 20.588 − 384 =
  21. 21.601 − 427 =
  22. 22.292 + 351 =
  23. 23.386 + 234 =
  24. 24.538 + 202 =
  25. 25.192 + 244 =
  26. 26.713 + 391 =
  27. 27.646 + 479 =
  28. 28.709 + 445 =
  29. 29.260 + 245 =
  30. 30.610 + 162 =
  31. 31.709 + 339 =
  32. 32.202 + 638 =
  33. 33.201 + 296 =
  34. 34.203 + 353 =
  35. 35.459 − 322 =
  36. 36.617 + 127 =
  37. 37.456 − 179 =
  38. 38.623 + 281 =
  39. 39.191 + 141 =
  40. 40.394 + 161 =

Answer key

  1. 706
  2. 750
  3. 1118
  4. 206
  5. 398
  6. 573
  7. 342
  8. 874
  9. 161
  10. 586
  11. 1004
  12. 220
  13. 859
  14. 223
  15. 130
  16. 711
  17. 873
  18. 471
  19. 248
  20. 204
  21. 174
  22. 643
  23. 620
  24. 740
  25. 436
  26. 1104
  27. 1125
  28. 1154
  29. 505
  30. 772
  31. 1048
  32. 840
  33. 497
  34. 556
  35. 137
  36. 744
  37. 277
  38. 904
  39. 332
  40. 555

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