Step 1
Standard notation of a number is when a number is written with only number digits and not in scientific notation.
E.g 1235679 is in standard notation
1.235679 x 10^6 is in scientific notation
Step 2
Write 6.43 x 10^7 in standard notation
![\begin{gathered} 10^7=\text{ 10000}000 \\ 6.43\text{ x 10000000= 64,300,000} \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/oyuy98n7kd5hcu8efhz86527mydz2v1b1g.png)
Hence the answer is option B