A squared +B squared=C squared 2.5 squared +B squared(stands for the hieght)=12 squared 6.25+B squared=144 B squared=144-6.25 B squared=137.75 then get the square root of 137.75 B=11.7
It's hard to line them up exactly straight, with all of their centers in a straight line. It's much easier if you line them up on the floor against a wall.
If you had 34 in a perfectly straight line, then the row would be
(34) times (18 millimeters) = 612 millimeters long .