Question

How do you write the number 420000 in standard form?

Answer 1

`4.2xx10^5`

Explanation:

A number expressed in `color(blue)"standard form"` is.

`color(red)(bar(ul(|color(white)(2/2)color(black)(axx10^n)color(white)(2/2)|)))`

`"where " -1<=a<10" and n is an integer"`

We have to write 420000 as a number between 1 and 10

The decimal point in 420000 is at `420000color(red)(•)`

and we want `4color(red)(•)20000` so that it is a value between 1 and 10

To place the decimal point back to it's original position means moving it 5 places to the right, effectively multiplying by 100000

`rArr4.2xx100000=4.2xx10^5larr" in standard form"`