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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 333 · 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. 1.651 + 203 =
  2. 2.744 − 603 =
  3. 3.965 − 171 =
  4. 4.736 − 191 =
  5. 5.226 + 203 =
  6. 6.198 + 452 =
  7. 7.293 + 451 =
  8. 8.149 + 118 =
  9. 9.770 − 224 =
  10. 10.846 − 529 =
  11. 11.944 − 824 =
  12. 12.519 − 194 =
  13. 13.318 + 424 =
  14. 14.699 + 331 =
  15. 15.763 + 138 =
  16. 16.243 + 201 =
  17. 17.158 + 397 =
  18. 18.968 − 132 =
  19. 19.525 + 435 =
  20. 20.620 + 268 =
  21. 21.877 − 232 =
  22. 22.238 + 491 =
  23. 23.193 + 355 =
  24. 24.557 − 338 =
  25. 25.667 + 368 =
  26. 26.858 − 679 =
  27. 27.277 + 511 =
  28. 28.494 + 235 =
  29. 29.385 + 284 =
  30. 30.158 + 396 =
  31. 31.213 + 295 =
  32. 32.146 + 461 =
  33. 33.140 + 211 =
  34. 34.880 − 318 =
  35. 35.283 + 302 =
  36. 36.928 − 217 =
  37. 37.183 + 551 =
  38. 38.697 + 639 =
  39. 39.444 − 319 =
  40. 40.662 + 577 =

Answer key

  1. 854
  2. 141
  3. 794
  4. 545
  5. 429
  6. 650
  7. 744
  8. 267
  9. 546
  10. 317
  11. 120
  12. 325
  13. 742
  14. 1030
  15. 901
  16. 444
  17. 555
  18. 836
  19. 960
  20. 888
  21. 645
  22. 729
  23. 548
  24. 219
  25. 1035
  26. 179
  27. 788
  28. 729
  29. 669
  30. 554
  31. 508
  32. 607
  33. 351
  34. 562
  35. 585
  36. 711
  37. 734
  38. 1336
  39. 125
  40. 1239

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