These are all the sizes of computer modern roman ten in the system.
\font\one=cmr10 at 6.67pt\one
This is size 1000.
\font\two=cmr10 at 7.30pt\two
This is size 1095.
\font\three=cmr10 at 8.00pt\three
This is size 1200.
\font\four=cmr10 at 8.77pt\four
This is size 1315.
\font\five=cmr10 at 9.60pt\five
This is size 1440.
\font\six=cmr10 at 10.00pt\six
This is size 1500.
\font\seven=cmr10 at 10.95pt\seven
This is size 1643.
\font\eight=cmr10 at 11.52pt\eight
This is size 1728.
\bye
\font\nine=cmr10 at 12.00pt\nine
This is size 1800.
\font\ten=cmr10 at 13.82pt\ten
This is size 2074.
\font\eleven=cmr10 at 14.40pt\eleven
This is size 2160.
\font\twelve=cmr10 at 16.59pt\twelve
This is size 2488.
\font\thirteen=cmr10 at 17.28pt\thirteen
This is size 2592.
\font\fourteen=cmr10 at 19.91pt\fourteen
This is size 2986.
\font\fifteen=cmr10 at 20.73pt\fifteen
This is size 3110.
\font\sixteen=cmr10 at 24.88pt\sixteen
This is size 3732.
\font\seventeen=cmr10 at 29.86pt\seventeen
This is size 4479.
\bye