I would like to be able to do is to input a negative. All of the previous
posts seem to show how to show the result of subtracting a large number of
hours from a smaller number - The 1904 format will give the negative answers
results.

I would like to be able to enter -ve times such as -1hr 24m in one of the
input cells in order total a row of times e.g.

A1 B1 C1
2:00 -1:24 = 0:34 =sum(a1:b1) etc
2:00 -3:13 = -1:13

is this possible?

Thanks in advance