How to resolve rounding error in calculated column involving Date and Time?

Question

I have a custom list in SharePoint with two Date and Time columns, namely StartTime and EndTime. Now I want to calculate the difference between them, so I created a new calculated column Length and entered the formula like this:

=INT(([EndTime]-[StartTime])*1440)

It should return the duration between StartTime and EndTime in minutes. But in some situations, the result is off by 1. E.g. 8:30PM - 6:30PM = 119 minutes. I believe this must have been caused by floating point rounding error. But how do I prevent it? Or should I use a formula other than INT()?

Edit: I saw this exact same formula here, under Date and time formulas > Calculate the difference between two times > Total minutes between two times. But that only added to my confusion, why is something Microsoft used as an example not working as intended?

Answer 1

Finally, I got a hint from a colleague, the solution is really simple:

Change the formula to

=([EndTime]-[StartTime])*1440

And then set decimal place to 0. SharePoint will now round off the number correctly.