Hi,
We calculate no of minutes of break*100/60
For example if employee has taken 30 mins of break then,
30*100
---------- = 50, which we write as 0,50
60
for the example you gave ie 8;30 to 8:52 is total duration of 22 mins here we calculate like this
22*100
--------- = 37, we write as 0,37
60