6-2 Six Digit Grid Coordinate: Estimating

Suppose your are halfway
between grid line 25 and
grid line 26. Then the next
number is 5 and the first half
of your address is 255.

Now suppose you are 7/10
of the way between grid line
79 and 80 then the second
half of your address is 797.
Your address would be
255797.