If the last 2 digits of a four-digit number are interchanged, the new number obtained is greater than the original number by 72. What is the difference between the last two digits of the number?
Explanation:
Consider a 4-digit number – a b c d. The number formed by reversing the last two digits is – a b d c.
Given, 1000a + 100b + 10c + d - (1000a + 100b + 10d + c) = 72 9c - 9d = 72 c -d = 8.
Alternately, We could have safely ignored the first 2 digits, as they would have not mattered after subtraction, this gives us {for last 2 digits}. (10c + d) – (10d + c ) = 72 ⇒ 9(c – d) = 72 ⇒ c – d = 8
Hence, option (d).
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