Answer:
0.0000004
Explanation:
To write in standard form:
For each power of 10 bigger than 0, we add a zero at the end of the number.
For each power of 10 less than 0, we add a zero before the number(the first one before the decimal point).
In this question:
4x10^(-7)
7 zeros before the number 4, with the first before the decimal point. So
0.0000004