scientific notation means, we move the decimal dot over so that we leave only 1 digit to the left of the dot.
hmmm let's see
[tex]\bf 12300000000\implies \stackrel{\leftarrow \textit{10 slots over}}{12300000000}.0\implies 1.2300000000.0\times 10^{10} \\\\[-0.35em] ~\dotfill\\\\ ~\hfill 1.23\times 10^{10}~\hfill[/tex]