Unable to Replace correct Value

Hi Friends,

              I have one problem to solve Regarding Replace Function I given demo below.
I have one value as "6,16,160" but i need replace value only "6" as "0" not "16","160"
if i uing replace function
select replace('6,16,160','6','0')
it is given as "0,10,100"
But I need Answer as "0,16,160"
please any one known share me your knowledge.
 
          
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