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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 329 · 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. 1.133 + 446 =
  2. 2.401 + 126 =
  3. 3.410 + 131 =
  4. 4.907 − 638 =
  5. 5.604 − 178 =
  6. 6.546 − 195 =
  7. 7.227 + 207 =
  8. 8.472 − 119 =
  9. 9.776 − 201 =
  10. 10.740 − 611 =
  11. 11.138 + 448 =
  12. 12.613 + 598 =
  13. 13.670 − 546 =
  14. 14.388 + 406 =
  15. 15.433 − 176 =
  16. 16.475 − 224 =
  17. 17.881 − 212 =
  18. 18.788 + 512 =
  19. 19.453 + 548 =
  20. 20.712 − 171 =
  21. 21.921 − 428 =
  22. 22.665 + 384 =
  23. 23.434 + 614 =
  24. 24.598 − 296 =
  25. 25.444 − 262 =
  26. 26.523 − 129 =
  27. 27.656 + 599 =
  28. 28.254 + 511 =
  29. 29.601 − 205 =
  30. 30.702 + 581 =
  31. 31.213 + 176 =
  32. 32.602 − 225 =
  33. 33.441 + 547 =
  34. 34.139 + 209 =
  35. 35.441 − 201 =
  36. 36.953 − 853 =
  37. 37.536 + 592 =
  38. 38.217 + 346 =
  39. 39.591 − 176 =
  40. 40.442 + 425 =

Answer key

  1. 579
  2. 527
  3. 541
  4. 269
  5. 426
  6. 351
  7. 434
  8. 353
  9. 575
  10. 129
  11. 586
  12. 1211
  13. 124
  14. 794
  15. 257
  16. 251
  17. 669
  18. 1300
  19. 1001
  20. 541
  21. 493
  22. 1049
  23. 1048
  24. 302
  25. 182
  26. 394
  27. 1255
  28. 765
  29. 396
  30. 1283
  31. 389
  32. 377
  33. 988
  34. 348
  35. 240
  36. 100
  37. 1128
  38. 563
  39. 415
  40. 867

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