+0  
 
+1
155
1
avatar

The ''border number'' of an square is defined as the number of unit squares whose edges border the edges of the larger square. The border numbers of 1 x 1, 2 x 2, 3 x 3 ,4 x 4, and 5 x 5 squares are illustrated below. What is the border number of a 20 unit by 20 unit square?

  

Guest Jun 1, 2017
Sort: 

1+0 Answers

 #1
avatar+17693 
+1

An  n by n  square will have n edges on the top row, n edges on the bottom row, n - 2 edges on the left side and n - 2 edges on the right side for a total of  n + n + (n - 2) + (n - 2)  =  4n - 4 edges.

For a 20 x 20 square, there will be 4(20) - 4  =  80 - 4  =  76 edges.

The border number will be 76.

geno3141  Jun 1, 2017

14 Online Users

avatar
avatar
We use cookies to personalise content and ads, to provide social media features and to analyse our traffic. We also share information about your use of our site with our social media, advertising and analytics partners.  See details