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+GetSquareRoot: ; 13b87
+; Return the square root of de in b.
+
+; Rather than calculating the result, we take the index of the
+; first value in a table of squares that isn't lower than de.
+
+ ld hl, Squares
+ ld b, 0
+.loop
+; Make sure we don't go past the end of the table.
+ inc b
+ ld a, b
+ cp $ff
+ ret z
+
+; Iterate over the table until b**2 >= de.
+ ld a, [hli]
+ sub e
+ ld a, [hli]
+ sbc d
+
+ jr c, .loop
+ ret
+
+Squares: ; 13b98
+root set 1
+ rept $ff
+ dw root*root
+root set root+1
+ endr