Solution:
Given:
[tex](6.4\times10^5)-(5.4\times10^4)[/tex][tex]\begin{gathered} (6.4\times10^5)-(0.54\times10^5)=(6.4-0.54)\times10^5 \\ =5.86\times10^5 \end{gathered}[/tex]Also, we can rewrite the numbers as ordinary number and get the difference;
[tex]\begin{gathered} 640000-54000=586,000 \\ \\ As\text{ scientific notation;} \\ 586,000=5.86\times10^5 \end{gathered}[/tex]Therefore;
[tex](6.4\times10^5)-(5.4\times10^4)=5.86\times10^5[/tex]