The addition of natural numbers 

Operations with natural numbers I 

4. Complete this magic square. 

In every 4x4 magic square you will also get the same sum by adding up: the four central numbers, the four numbers in the corners of the square and the four numbers in the corners of each horizontal rectangle that can be formed with 6 cells. When clicking on Init a new magic square will appear at random. 
Eduardo Barbero Corral  
Spanish Ministry of Education. Year 2007  
Except where otherwise
noted, this work is licensed under a Creative
Common License