Question

How do you write `4.2 * 10^-4` in standard form?

Answer 1

`4.2xx10^(-4)=0.00042`

Explanation:

In scientific notation, we write a number so that it has single digit to the left of decimal sign and is multiplied by an integer power of `10`.

In other words, in scientific notation, a number is written as `axx10^n`, where `1<=a<10` and `n` is an integer and `1<=a<10`.

To write the number in normal or standard notation one just needs to multiply by the power `10^n` (or divide if `n` is negative). This means moving decimal `n` digits to right if multiplying by `10^n` and moving decimal `n` digits to left if dividing by `10^n` (i.e. multiplying by `10^(-n)`).

In the given case, as we have the number as `4.2xx10^(-4)`, we need to move decimal digit to the left by four points. For this, let us write `4.2` as `00004.2` and moving decimal point four points to left means `0.00042`

Hence in standard notation `4.2xx10^(-4)=0.00042`