Answer
$\frac{1}{17576000}$
Work Step by Step
We know that $probability=\frac{\text{number of favourable outcomes}}{\text{number of all outcomes}}$
The number of good outcomes is $1$
The number of all outcomes is $10^{3}\cdot26^3=17576000$
Hence the probability here is: $\frac{1}{17576000}$
