Respuesta :

              there r total 10 digits (0-9)
the first digit cannot be zero so we have only 9 options for the first digit (1-9)
the second digit can have only 9 options as we cannot repeat the digit used in the first place, but we can use 0.
the third digit has now 8 options left out of ten, as we cannot repeat digits.

the solution is
9C1+9C1+8C1
=9*9*8
=648 answer

the correct answer is 648 turned this in already and got it right. Hoped the helped u.
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