Question
If a ten-digit number 57a61395z2 is divisible by 72, then
find the number of possible values of ‘a’.Solution
ATQ,
Since, the number 57a61395z2 is divisible by 72, therefore it has to be divisible by 8 and 9, individually
If the number is divisible by 8, therefore last three digits should be divisible by 8
Hence, z = 0, 4 and 8
Now, check divisibility by 9
When z = 0, sum of the digits = 47 + a
Hence, a = 2
When z = 4, sum of the digits = 51 + a
Hence, a = 3
When z = 8, sum of the digits = 55 + a
Hence, a = 1
Therefore, number of possible values of a = 3
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