php - Why i am getting error in this Addition and subtraction in PHP5.6.8 -

i using php 5.6.8 version in xampp server. in getting error in output in output addition , sub time got output code

    <?  echo"hello php"."&nbsp;". "whats up"."<br/>"; echo "adding". 2+2 ."<br/>"; echo "sub".3-2 ."<br/>"; echo "mul". 2*2 ."<br/>"; echo "div". 2/2 ."<br/>"; echo "moduls". 5%2 ."<br/>"; ?> 

output

hello php whats 2 -2 mul4 div1 moduls1 

try using ,(comma) instead of .(dot). because of operator precedence , how precedence operator work there's answer within why doesn't html br break line tag doesn't work in code? answered rizier123

echo"hello php"."&nbsp;". "whats up"."<br/>"; echo "adding", 2+2 ,"<br/>"; echo "sub", 3-2 ,"<br/>"; echo "mul", 2*2 ,"<br/>"; echo "div", 2/2 ,"<br/>"; echo "moduls", 5%2 ,"<br/>";