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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 203 · 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. 1.729 + 621 =
  2. 2.610 + 242 =
  3. 3.129 + 577 =
  4. 4.331 + 309 =
  5. 5.553 + 371 =
  6. 6.644 + 575 =
  7. 7.733 + 546 =
  8. 8.178 + 268 =
  9. 9.519 − 157 =
  10. 10.178 + 681 =
  11. 11.660 − 269 =
  12. 12.160 + 548 =
  13. 13.699 + 212 =
  14. 14.698 − 248 =
  15. 15.613 − 249 =
  16. 16.768 + 554 =
  17. 17.575 − 164 =
  18. 18.879 − 356 =
  19. 19.376 + 581 =
  20. 20.974 − 457 =
  21. 21.281 + 314 =
  22. 22.618 − 491 =
  23. 23.155 + 151 =
  24. 24.456 − 235 =
  25. 25.273 + 622 =
  26. 26.312 + 269 =
  27. 27.514 + 444 =
  28. 28.461 + 598 =
  29. 29.200 + 367 =
  30. 30.964 − 762 =
  31. 31.140 + 282 =
  32. 32.240 + 534 =
  33. 33.852 − 571 =
  34. 34.412 − 166 =
  35. 35.764 + 634 =
  36. 36.620 + 484 =
  37. 37.951 − 714 =
  38. 38.575 − 334 =
  39. 39.667 − 469 =
  40. 40.815 − 289 =

Answer key

  1. 1350
  2. 852
  3. 706
  4. 640
  5. 924
  6. 1219
  7. 1279
  8. 446
  9. 362
  10. 859
  11. 391
  12. 708
  13. 911
  14. 450
  15. 364
  16. 1322
  17. 411
  18. 523
  19. 957
  20. 517
  21. 595
  22. 127
  23. 306
  24. 221
  25. 895
  26. 581
  27. 958
  28. 1059
  29. 567
  30. 202
  31. 422
  32. 774
  33. 281
  34. 246
  35. 1398
  36. 1104
  37. 237
  38. 241
  39. 198
  40. 526

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