Saturday, 1 December 2012

How many 3-digit even numbers can be formed from the digits 1,2,3,4,5 and 6 if the digits can be repeated?

How many 3-digit even numbers can be formed from the digits 1,2,3,4,5 and 6 if the digits can be repeated?

Sol : 

Let 2 be fixed at unit's place . The ten's place can be filled up in six ways. The hundred's place can also be filled in six ways.

No. of numbers that can be formed when 2 is at unit's place  =  6x6 = 36.

Similarly when 4 is at unit's place, the number of numbers that can be formed = 36.

Again when 6 is at unit's place, The number of numbers that can be formed = 36.

Therefore   The total numbers of ways when 3-digits numbers can be formed, the digits being repeated = 36 x 3 = 108......

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