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Question
For what value of n, 2n ✕ 5n ends in 5.
Solution
We need to find the value of n, for which `2^nxx5^n` ends in 5.
Clearly,
`2^nxx5^n = (2xx5)6n`
`10^n`
Also, all the values of n will make `10^n` end in 0.
Thus, there is no value of n for which `2^nxx5^n ` ends in 5.
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