I\'m trying to convert a large time value in excel to a decimal number for hours.
I currently have a column adding up \"Ready time\" for a call centre which is 3545:20:0
Excel counts in days (1 day = 1) so for hours you just multiply by 24, i.e.
=M54*24
format result cell as number with required number of decimals
[the reason your current formula fails is because of DAY
function - DAY
is day of the month so it fails for you when the time value is >= 32*24 = 768 hours]