let\'s translate to decimal like this:
6∙9^{2}+3∙9^{1}+7∙9^{0} = 6∙81+3∙9+7∙1 = 486+27+7 = 520_{10}
got It: 637_{9} =520_{10}
Translate the number 520_{10} в 5  false like this:
the Integer part of the number is divided by the base of the new number system:
520  5    
520  104  5   
0  100  20  5  
 4  20  4  
  0   

the result of the conversion was:
520_{10} = 4040_{5}
the Final answer: 637_{9} = 4040_{5}