This is closest to 6 tenths in units or 6-1/4 tenths if fractions are allowed.
6 7's
5/8 inch is 15.875mm
8*7/10 = 56/10 = 5.6 eighths
1
5.203125 eights
8
1
1.25 tenths of an inch.
10......
There are ten tenths in anything.
3/8 inch is 9.525 millimeters.
128 of them.