var a=prompt("Entre a:","3.1416");[br]a=a+a; //concatenate string[br]var b=parseInt(prompt("Entre b:","3.1416"));[br]b=b+b; //add int[br]var c=parseFloat(prompt("Entre c:","3.1416"));[br]c=c+c; //add real[br]//var d=parseDouble(prompt("Entre d:","3.1416"));[br]//ReferenceError: "parseDouble" is not defined. (Error at line:#7)[br]//d=d+d;[br]//alert("a="+a+"\n b="+b+"\n c="+c+"\n d="+d+"\n");[br]var e=Number(prompt("Entre e:","3.1416"));[br]e=e+e; //add real[br]alert("a="+a+"\nb="+b+"\nc="+c+"\ne="+e+"\n");