To convert \(6.4 \times 10^5\) into standard form, we first need to interpret what that means. The expression \(6.4 \times 10^5\) means 6.4 multiplied by \(10\) raised to the power of \(5\).
Calculating this:
\[ 6.4 \times 10^5 = 6.4 \times 100000 = 640000 \]
Therefore, in standard form, \(6.4 \times 10^5\) represents the number 640,000.
So, the correct answer is:
- 640,000 (or 64,000 if written without grouping commas).