# How much is 70 degrees Fahrenheit in Celsius?

Mar 12, 2017

${70}^{\circ} F = 21. {\overline{1}}^{\circ} C$

#### Explanation:

To convert Fahrenheit to Celsius, the normal method is to subtract $32$ then divide by $1.8$ (i.e. $\frac{9}{5}$).

So in our example:

$\frac{5}{9} \left(70 - 32\right) = \frac{5}{9} \left(38\right) = \frac{190}{9} = 21. \overline{1}$

Alternatively, since $- {40}^{\circ} F = - {40}^{\circ} C$, we can convert by adding $40$, multiplying by $\frac{5}{9}$, then subtracting $40$:

$\frac{5}{9} \left(70 + 40\right) - 40 = \frac{5}{9} \left(110\right) - 40 = \frac{550}{9} - 40 = 61. \overline{1} - 40 = 21. \overline{1}$

The reverse conversion from Celsius to Fahrenheit can be done by either of the following:

• Multiply by $\frac{9}{5}$ then add $32$.

• Add $40$, multiply by $\frac{9}{5}$, then subtract $40$.