I'm trying to write a calculator program in assembly for the Apple //e. I know that there are built-in subroutines for performing all kinds of math operations involving the floating-point accumulator (FAC), and I'd like to use those, but I don't know how to convert the set of hex digits the user inputs into memory into the format required for the FAC (exponent + mantissa, explained in great detail on p.100 of "Inside the Apple IIe" by Gary B. Little). I know about `FRMNUM` (`$DD67`) and `PRNTFAC` (`$ED2E`), but I can't find the subroutine that Applesoft uses to take a decimal number and convert it to the six-bit exponent-mantissa format. 

EDIT 1: [Here][1] is a link to the calculator program I'm working on. I can't copy and paste it into here because it's too long. 

EDIT: Here's the commented data in text format. 

 *=============
 * PRNTFAC TEST
 
 	 ORG	$6000
 
 HOME	EQU	$FC58
 FRMNUM	EQU	$DD67
 PRNTFAC	EQU	$ED2E
 TXTPTR	EQU	$B8
 PTR	 EQU	$06
 
 * CLEAR SCREEN
 
 START	 JSR	HOME
 
 * MAKE BOTH POINTER AND TXTPTR
 * POINT TO $7000
 
 	 LDA	#$00
 	 STA	PTR
 	 STA	TXTPTR
 	 LDA	#$70
 	 STA	PTR+1
 	 STA	TXTPTR+1
 
 * LOAD CONTENT OF DATA
 * TO $7000
 
 	 LDX	#$00
 	 LDY	#$00
 ]LOOP	 LDA	DATA,X
 	 STA	(PTR),Y
 	 BEQ	NEXT
 	 INX
 	 INY
 	 JMP	]LOOP
 
 * $0700 NOW CONTAINS
 * 31 C8 31 00 (I HAVE CHECKED
 * THIS USING THE DEBUGGER)

 * RUN FRMNUM
 
 NEXT	JSR	FRMNUM
 
 * RUN PRNTFAC
 * IF PRNTFAC OPERATES LIKE
 * COUT, A "2" SHOULD BE PRINTED
 * AT THE TOP LEFT CORNER OF THE
 * SCREEN
 
 	 JSR	PRNTFAC
 
 END	 RTS
 
 DATA	HEX	31C83100


 [1]: https://drive.google.com/file/d/1vPZLT7GnqId05UTHo7mTxDXuzoWi9dmq/view?usp=sharing