6 answers
(click or scroll down)
the chain is made with 3 lines per square, plus one ending line
3*35+1
3*35+1
RR
RB
BB
Each square has four sides, and the sides of adjacent squares can be shared. So, if we represent each square with a line segment, we can see that two line segments are needed for each square to create its top and right sides.
Since we want to make a row of 35 squares, we need to have 35 line segments for the top and 35 line segments for the right sides of the squares. Therefore, a total of 2 * 35 = 70 line segments are needed to make the row of 35 squares.