Question

How do you write `4times10^-4` in standard form?

Answer 1

`x xx 10^(-4)=color(green)(1/2500)` or `color(green)(0.0004)`

Explanation:

It depends upon what you (or your instructor) means by "standard form" for a number. (I have seen it used to mean "scientific notation" but that is obviously not the intent in this case).

As a rational fraction:
`color(white)("XXX")4xx 10^(-4) = 4 xx 1/(10^4) = 4/10000= 1/2500`

As a decimal fraction:
`color(white)("XXX")4xx10^(-4)=0.4xx10^(-3)=0.04xx10^(-2)=0.004xx10^(-1)=0.0004xx10^0=0.0004`