DAY 33

Comment

Imagine removing the blue square.
How many 1 cm long edges are removed from the original perimeter?
How many new 1 cm edges are exposed?

Answer

36 cm.

Readers' methods

Adam M, Holmer Green HP11
By removing the blue square you subtract 3 cm and change it to 1 cm.
That is a difference of 2, so subtract 2 from 38 cm
= 36 cm.