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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 695 · 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. 1.148 + 348 =
  2. 2.140 + 301 =
  3. 3.483 − 341 =
  4. 4.404 + 219 =
  5. 5.556 − 404 =
  6. 6.498 + 568 =
  7. 7.235 + 247 =
  8. 8.436 + 243 =
  9. 9.290 + 492 =
  10. 10.545 + 499 =
  11. 11.284 + 271 =
  12. 12.962 − 248 =
  13. 13.499 − 195 =
  14. 14.314 + 388 =
  15. 15.488 − 372 =
  16. 16.949 − 454 =
  17. 17.773 + 501 =
  18. 18.350 + 602 =
  19. 19.459 − 301 =
  20. 20.301 + 647 =
  21. 21.566 + 463 =
  22. 22.769 + 505 =
  23. 23.503 + 573 =
  24. 24.140 + 366 =
  25. 25.433 + 223 =
  26. 26.310 + 345 =
  27. 27.177 + 159 =
  28. 28.571 − 391 =
  29. 29.330 + 285 =
  30. 30.468 − 159 =
  31. 31.663 + 583 =
  32. 32.486 − 295 =
  33. 33.685 + 259 =
  34. 34.977 − 716 =
  35. 35.591 − 179 =
  36. 36.292 + 488 =
  37. 37.969 − 714 =
  38. 38.606 − 211 =
  39. 39.269 + 255 =
  40. 40.343 + 166 =

Answer key

  1. 496
  2. 441
  3. 142
  4. 623
  5. 152
  6. 1066
  7. 482
  8. 679
  9. 782
  10. 1044
  11. 555
  12. 714
  13. 304
  14. 702
  15. 116
  16. 495
  17. 1274
  18. 952
  19. 158
  20. 948
  21. 1029
  22. 1274
  23. 1076
  24. 506
  25. 656
  26. 655
  27. 336
  28. 180
  29. 615
  30. 309
  31. 1246
  32. 191
  33. 944
  34. 261
  35. 412
  36. 780
  37. 255
  38. 395
  39. 524
  40. 509

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