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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 93 · 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. 1.161 + 308 =
  2. 2.589 − 261 =
  3. 3.448 − 288 =
  4. 4.554 − 157 =
  5. 5.986 − 267 =
  6. 6.506 − 325 =
  7. 7.605 − 316 =
  8. 8.518 + 614 =
  9. 9.787 − 328 =
  10. 10.255 + 382 =
  11. 11.562 + 391 =
  12. 12.870 − 383 =
  13. 13.940 − 364 =
  14. 14.745 + 584 =
  15. 15.652 − 407 =
  16. 16.569 − 371 =
  17. 17.685 + 612 =
  18. 18.616 − 162 =
  19. 19.595 + 581 =
  20. 20.621 − 274 =
  21. 21.490 + 536 =
  22. 22.585 − 306 =
  23. 23.967 − 381 =
  24. 24.288 + 553 =
  25. 25.552 − 321 =
  26. 26.582 + 244 =
  27. 27.549 − 171 =
  28. 28.295 + 281 =
  29. 29.447 + 253 =
  30. 30.627 − 252 =
  31. 31.744 + 146 =
  32. 32.756 + 625 =
  33. 33.976 − 561 =
  34. 34.368 + 318 =
  35. 35.912 − 211 =
  36. 36.390 + 683 =
  37. 37.714 + 131 =
  38. 38.314 + 537 =
  39. 39.504 − 357 =
  40. 40.418 − 237 =

Answer key

  1. 469
  2. 328
  3. 160
  4. 397
  5. 719
  6. 181
  7. 289
  8. 1132
  9. 459
  10. 637
  11. 953
  12. 487
  13. 576
  14. 1329
  15. 245
  16. 198
  17. 1297
  18. 454
  19. 1176
  20. 347
  21. 1026
  22. 279
  23. 586
  24. 841
  25. 231
  26. 826
  27. 378
  28. 576
  29. 700
  30. 375
  31. 890
  32. 1381
  33. 415
  34. 686
  35. 701
  36. 1073
  37. 845
  38. 851
  39. 147
  40. 181

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