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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 365 · 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. 1.630 + 374 =
  2. 2.583 − 444 =
  3. 3.737 + 588 =
  4. 4.473 + 407 =
  5. 5.701 + 507 =
  6. 6.719 + 608 =
  7. 7.378 + 551 =
  8. 8.486 − 131 =
  9. 9.245 + 118 =
  10. 10.272 + 407 =
  11. 11.422 + 317 =
  12. 12.702 + 259 =
  13. 13.239 + 556 =
  14. 14.141 + 262 =
  15. 15.730 + 566 =
  16. 16.419 − 291 =
  17. 17.784 + 631 =
  18. 18.314 + 322 =
  19. 19.422 − 225 =
  20. 20.780 − 601 =
  21. 21.586 + 304 =
  22. 22.772 + 344 =
  23. 23.442 + 206 =
  24. 24.741 − 611 =
  25. 25.671 + 514 =
  26. 26.454 − 335 =
  27. 27.432 − 177 =
  28. 28.352 + 497 =
  29. 29.160 + 539 =
  30. 30.729 − 582 =
  31. 31.601 − 124 =
  32. 32.830 − 712 =
  33. 33.630 + 304 =
  34. 34.498 − 248 =
  35. 35.607 − 123 =
  36. 36.562 − 381 =
  37. 37.418 − 262 =
  38. 38.967 − 435 =
  39. 39.270 + 343 =
  40. 40.187 + 234 =

Answer key

  1. 1004
  2. 139
  3. 1325
  4. 880
  5. 1208
  6. 1327
  7. 929
  8. 355
  9. 363
  10. 679
  11. 739
  12. 961
  13. 795
  14. 403
  15. 1296
  16. 128
  17. 1415
  18. 636
  19. 197
  20. 179
  21. 890
  22. 1116
  23. 648
  24. 130
  25. 1185
  26. 119
  27. 255
  28. 849
  29. 699
  30. 147
  31. 477
  32. 118
  33. 934
  34. 250
  35. 484
  36. 181
  37. 156
  38. 532
  39. 613
  40. 421

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