EgmatQuantExpert wrote:

A 3-character alpha-numeric code does have the following properties – the first character can be any number except 0 and 9, the second character can be any small letter between a to z, excluded, and the third character can have any of those characters possible for the first two places. How many such codes can be formed?

A. 26

B. 64

C. 520

D. 6144

E. 9360

The 3 character alpha-numeric code has the following characters

First character - Any number except 0 and 9 - Total of 10 - 2 = 8 possibilities

Second character - Any small letter except a and z - Total of 26 - 2 = 24 possibilities

Third character - Any number except 0 and 9 or Any small letter except a and z - Total of 8 + 24 = 32 possibilities

In this case, to find the total number of possibilities, we can use the unit's digit to find the

answer as number ending 8 * number ending 4 * number ending 2 is a number ending 4.

Also, the answer must be close to 10*20*30 is a little more than 6000.

P.S when the answer options are far apart, we can use approximations to arrive at the answerTherefore,

Option D(6144) is the the total number of 3-character alpha-numberic codes.

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