Directly send it to register and read it out. It's read in both case of hexa or decimal. You don't have to convert it. Try with Nigel tutorial (see from his signature in this forum). He gave a wonderful workart to work with LCD displayer.
If you intend to do an convert algorithm get this.
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38h-3b h are locations where equvalent ascii values of corros dec no will b stored
byte hi n lo are hex nos to b converted
in lcd routine...u can ask to display contents of loc 38-3b h