Give two rational numbers lying between 0.515115111511115...0.5353353335...
Let $a=0.515115111511115 \ldots$ and $b=0.535335333533335 \ldots$
are non-terminating and non-repeating. So we observe that in first decimal place have the same digit but digit in the second place of their decimal representation are distinct. And the number a has 1 and b has 3. So a < b.
Hence two rational numbers are $0.5152,0.532$ lying between $0.515115111511115 \ldots$ and $0.535335333533335 \ldots$