TKWatch is a electric calculator for time calculation.
It can calculate only minutes and seconds.(neither hour nor time less than one second)
It can display process of calculation, so you can check your inputs.
You can cancel last input by tapping "C" key.
It also have a stopwatch.
I developped TKWatch for broadcasting staff.
You can calculate as "1m20s+2m30s=3m50s" using "Min" and "Sec" key.
Also, for abbreviation, you can calculate as "120+230=350".
TKWatch blocks error inputs like "3m35m", "2s45" or number over 4 figures.
Upper part of stopwatch displays time.
"±" button adjust time of TKWatch.