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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 479 · 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. 1.269 + 556 =
  2. 2.596 − 291 =
  3. 3.382 + 576 =
  4. 4.445 − 122 =
  5. 5.136 + 518 =
  6. 6.180 + 283 =
  7. 7.694 + 143 =
  8. 8.758 − 541 =
  9. 9.513 + 396 =
  10. 10.484 + 419 =
  11. 11.618 + 221 =
  12. 12.184 + 211 =
  13. 13.556 + 275 =
  14. 14.554 − 416 =
  15. 15.301 + 257 =
  16. 16.511 − 179 =
  17. 17.277 + 252 =
  18. 18.624 − 171 =
  19. 19.686 + 555 =
  20. 20.656 − 471 =
  21. 21.814 − 324 =
  22. 22.930 − 594 =
  23. 23.589 + 579 =
  24. 24.304 + 243 =
  25. 25.665 + 489 =
  26. 26.157 + 588 =
  27. 27.548 + 443 =
  28. 28.493 − 168 =
  29. 29.852 − 473 =
  30. 30.462 − 265 =
  31. 31.616 + 408 =
  32. 32.561 − 334 =
  33. 33.847 − 289 =
  34. 34.755 + 591 =
  35. 35.911 − 425 =
  36. 36.778 − 521 =
  37. 37.647 − 262 =
  38. 38.453 − 274 =
  39. 39.284 + 116 =
  40. 40.194 + 593 =

Answer key

  1. 825
  2. 305
  3. 958
  4. 323
  5. 654
  6. 463
  7. 837
  8. 217
  9. 909
  10. 903
  11. 839
  12. 395
  13. 831
  14. 138
  15. 558
  16. 332
  17. 529
  18. 453
  19. 1241
  20. 185
  21. 490
  22. 336
  23. 1168
  24. 547
  25. 1154
  26. 745
  27. 991
  28. 325
  29. 379
  30. 197
  31. 1024
  32. 227
  33. 558
  34. 1346
  35. 486
  36. 257
  37. 385
  38. 179
  39. 400
  40. 787

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