# How to simplify 5 times 4.0 times 10^-4 in scientific notation?

Nov 4, 2015

$5 \times 4.0 \times {10}^{-} 4 = 2 \times {10}^{-} 3$

#### Explanation:

$5 \times 4.0 \times {10}^{-} 4$

Multiply $5 \times 4$.

$20 \times {10}^{-} 4$

Move the decimal to the left one place so that the coefficient has one non-zero digit in front of the decimal, and add $1$ to the exponent.

$20 \times {10}^{-} 4 =$

$2 \times {10}^{- 4 + 1} =$

$2 \times {10}^{-} 3$

Note: Since $5$ has only one significant figure, and we are multiplying, the answer can have only one significant figure. Therefore, the coefficient must be $2$ and not $2.0$, which has two significant figures.