# How do you round 0.00222755 to four significant figures and express the result in scientific notation?

Mar 1, 2016

Let's do this one at a time

#### Explanation:

Significant figures
Start counting from the first non-zero. In this case the $7$ is the fourth significant figure. Since this is followed by a $5$ we will have to round up (0-4=down, 5-9=up).
$0.002228$

Scientific notation
Is of the form $a \times {10}^{b}$ where $a$ is a number with just one non-zero digit in front of the decimal point. To get there, we have to move the decimal point 3 to the right. Thus 3 means an exponent of 3, to the right means it is negative:
$2.228 \times {10}^{-} 3$

You could also have done it this way:
$0.002228 = \frac{2.228}{1000} = \frac{2.228}{10} ^ 3 = 2.228 \times {10}^{-} 3$