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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 603 · 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. 1.181 + 275 =
  2. 2.508 + 486 =
  3. 3.570 − 191 =
  4. 4.610 − 254 =
  5. 5.613 + 226 =
  6. 6.164 + 113 =
  7. 7.271 + 362 =
  8. 8.798 − 646 =
  9. 9.720 + 412 =
  10. 10.511 − 177 =
  11. 11.550 + 597 =
  12. 12.134 + 364 =
  13. 13.531 − 331 =
  14. 14.508 + 656 =
  15. 15.733 − 247 =
  16. 16.298 + 207 =
  17. 17.464 − 296 =
  18. 18.494 + 358 =
  19. 19.433 − 135 =
  20. 20.752 − 206 =
  21. 21.864 − 274 =
  22. 22.973 − 329 =
  23. 23.534 − 137 =
  24. 24.485 − 355 =
  25. 25.775 + 238 =
  26. 26.182 + 268 =
  27. 27.430 − 128 =
  28. 28.839 − 432 =
  29. 29.465 + 261 =
  30. 30.580 − 198 =
  31. 31.840 − 563 =
  32. 32.460 + 594 =
  33. 33.283 + 489 =
  34. 34.774 + 173 =
  35. 35.679 + 358 =
  36. 36.383 + 416 =
  37. 37.353 + 168 =
  38. 38.755 + 402 =
  39. 39.649 + 542 =
  40. 40.380 + 218 =

Answer key

  1. 456
  2. 994
  3. 379
  4. 356
  5. 839
  6. 277
  7. 633
  8. 152
  9. 1132
  10. 334
  11. 1147
  12. 498
  13. 200
  14. 1164
  15. 486
  16. 505
  17. 168
  18. 852
  19. 298
  20. 546
  21. 590
  22. 644
  23. 397
  24. 130
  25. 1013
  26. 450
  27. 302
  28. 407
  29. 726
  30. 382
  31. 277
  32. 1054
  33. 772
  34. 947
  35. 1037
  36. 799
  37. 521
  38. 1157
  39. 1191
  40. 598

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