Need help about Time addition and time difference topics

Dear all, im am hoping that you guys could help me solving this problem

I would like to set the current time manually and then after few minute , i would like to input again the current time. Now, having this the two given value, i want to show the time difference between the two values in minutes. How can i possibly do that. I have tried several attempts regarding time figures but cant solve it. Hope you guys could help. Thank a lot in advance.

Hello @ian8833,
Did you try "decimal-date-time" . Once look at this link . Hope it helps.

Thanks and Regards,