<p>Here it goes:</p>
<p>A rectangle that measures 4cm by 6 cm is divided into 24 squares with sides 1 cm in length. What is the total number of 1 cm long sides in those 24 squares?
(Note: if 2 squares share a side, the side should be counted only once)</p>
<p>The answer is 58, but why?</p>
<p>Thank!!</p>
<p>Consider the fact that to make 4 spaces, you need 5 lines to separate each of those spaces, thus you will have 7 vertical lines at 4 cm each and 5 horizontal lines at 6 cm each.</p>
<p>Then you just multiply and add to get 58. (7<em>4)+(5</em>6)=58</p>
<p>^Yes. And it will help if you DRAW the big rectangle. First count all the “vertical” sides, then the horizontal ones.</p>
<p>Why wouldn’t it work if I do 24 x 4?</p>
<p>^ because you will overcount some of the sides.</p>
<p>that makes sense. thanks!</p>