How do you work out the upper quartile?

the upper quartile can be calculate by:

(n+1)x3/4 where n is the number of data points.

The upper quartile is the median (middle) of the upper half of a data set. This is located by dividing the data set with the median and then dividing the upper half that remains with the median again, this median of the upper half is the upper quartile.

Upper quartile (Q3) = (N+1)*(3/4)