1:30+0:42=2:12
Type 1 then press ''' (''' is button to the left of HYP and above ENG)
Type 3 and 0 then press ''' again.
This will display 1.5 (decimal form)
Now press SHIFT (left upper most button) and press '''
This should display 1'30'' ( hr and min)
Press + then type 0 then press ''' again.
Type 4 and 2 then press '''
This will display .7 (decimal form)
Press SHIFT then press ''' to display 0'42''(hr and min)
Press =
This should give the answer in decimal form
Press SHIFT then press ''' to view in hr and min.
You may ommit SHIFT ''' to add in decimal form and after the sum is displayed press SHIFT''' to display it in hr and min.
I hope this helps