Addition of integer numbers. Part of a series in <a href="//commons.wikimedia.org/wiki/User:Kismalac/conjuntos" title="User:Kismalac/conjuntos">elementary mathematics</a>.
<a href="//commons.wikimedia.org/wiki/User:Kismalac" title="User:Kismalac">kismalac</a>
<span class="int-own-work" lang="en">Own work</span>