To work it out, you just need to know that there are *12 inches in a foot* and *2.5 cm in an inch* (roughly).

We want to convert 5 ft 8 in to cm.

5 ft = 5 x 12 = 60 in

Now add the 8 to 60, as we have quantities in the same unit

60 + 8 = 68 inches.

Now multiply by 2.5

There is an ease way to accomplish this:

2.5 = 25/10 = 5/2. So, to find the answer, you can multiply by 5 and divide by 2.

(60 + 8) x 5/2 = (300 + 40)/2 = 150 +20 = 170 cm

This is an approximation in fact there are 2.54 cm in an inch. If you want to get a precise answer, it's better to use an online calculator like this one:

Feet and inches to cm calculator