# How do you find the scientific notation for a decimal?

The key is to respect the scientific notation formula $a \cdot {10}^{n}$ where $1 \le a < 10$
Let us take a decimal such as 645.789. To get a where $1 \le a < 10$, we need to move the decimal place 2 spots to the left.
Which is the same as dividing by ${10}^{2} = 100$
So we have $6.4578 \cdot {10}^{2}$ as our scientific notation of 645.789.