# This expression, 1.8C + 32, shows how to convert from degrees Celsius to degrees Fahrenheit, where C represents the temperature in degrees Celsius. What is the temperature in degrees Fahrenheit when the temperature is 25°C?

Jan 5, 2017

${77}^{\circ} F$

#### Explanation:

If you notice that $1.8 = \frac{18}{10}$
then this can be done (or almost done) in your head:

$\frac{18}{10} \cdot 25 + 32$

$\textcolor{w h i t e}{\text{XXX}} = \frac{18}{2} \cdot 5 + 32$

$\textcolor{w h i t e}{\text{XXX}} = 9 \cdot 5 + 32$

$\textcolor{w h i t e}{\text{XXX}} = 45 + 32$

$\textcolor{w h i t e}{\text{XXX}} = 77$