I have 10 cells with 4 digit numbers each example : a1=4598, a2=5741
and so on until you get to a10=7125 Ok?
What function do I use to reteieve the largest of the first digit of
each entry? obviously I am dealing with thousands of cells.
In the above example the largest first digit of the three cells is 7
how do I automate this for thousands of cells.

Maybe this'll help:
=INT(MAX(A1:J1)/1000)