Solution:
surface area of a piece of paper = 137 sq cm
Use the fact that 10 mm = 1 cm to convert this area to mm^2
[tex]1\ cm = 10\ mm[/tex]
Then,
[tex]1\ cm^2 = 100\ mm^2[/tex]
Convert 137 sq cm to sq mm
[tex]137\ cm^2 = 137 \times 100\ mm^2\\\\137\ cm^2 = 13700\ mm^2[/tex]
Thus, surface area of a piece of paper is [tex]13700\ mm^2[/tex]