A calculator as a list of numbers and operators
JavaScript (ES6) 53

A function taking an array as input.

Run the snippet in Firefox to test.



f=a=&gt;a.map(t=&gt;t&lt;'0'?o=t:v=eval(v+o+t)|0,v=0,o='+')&amp;&amp;v

// TEST
out=x=&gt;O.innerHTML=x;

input = [5,8,25,"*",9,6,2,"-",104,"/",4,7,"+",6,"%",14];
out(input.join(' ')+' -&gt; '+f(input));

function go() {
  i=I.value.split(/ +/),out(I.value+' -&gt; '+f(i))
}  
&lt;pre id=O&gt;&lt;/pre&gt;
Your test:&lt;input id=I&gt;&lt;button onclick='go()'&gt;GO&lt;/button&gt;