A number consists of three digits of which the middle one is zero and their sum is 4. If the number formed by interchanging the first and last digits is greater than the number itself by 198, then the difference between the first and last digits is
Let the three-digits number be 100a + 10b + c.
b = 0
a + b + c = 4, or a + c = 4 (This information is not required)
100c + a = 100a + c + 198
99c - 99a = 198
99(c - a) = 198
c - a = 2
The correct option is B.