An integer is said to be “diverse” if no two of its digits are the same. For example, 327 is “diverse” but 404 is not. How many “diverse” two digit numbers are there ?
Choose the correct choice from the following choices:
A) 70	B) 72	C) 81	D) 90	E) 91
A two digit number has to be formed from digits 0 to 9 such that unit's digit and ten's digit are not same.   The unit's digit can have 10 values from 0 to 9.   Ten's digit can have 9 values from 1 to 9   So total number of two digit numbers will be 9 x 10 = 90   But there are 9 numbers which are not diverse.   11,22,33,44,55,66,77,88,99   so, the number of diverse two digit numbers will be  90-9= 
<gadget id="calculator"> 90-9</gadget>
<output>81</output>
81   Answer:- 81
<result>C</result>
An integer is said to be “diverse” if no two of its digits are the same. For example, 327 is “diverse” but 404 is not. How many “diverse” two digit numbers are there ?