<P> Leonhard Euler used an open variant of the symbol in order to denote "absolutus infinitus". Euler freely performed various operations on infinity, such as taking its logarithm . This symbol is not used anymore, and is not encoded as a separate character in Unicode . </P> <P> In mathematics, the infinity symbol is used more often to represent a potential infinity, rather than to represent an actually infinite quantity such as the ordinal numbers and cardinal numbers (which use other notations). For instance, in the mathematical notation for summations and limits such as </P> <Dl> <Dd> ∑ n = 0 ∞ 1 2 n = lim x → ∞ 2 x − 1 2 x − 1 = 2, (\ displaystyle \ sum _ (n = 0) ^ (\ infty) (\ frac (1) (2 ^ (n))) = \ lim _ (x \ to \ infty) (\ frac (2 ^ (x) - 1) (2 ^ (x-1))) = 2,) </Dd> </Dl> <Dd> ∑ n = 0 ∞ 1 2 n = lim x → ∞ 2 x − 1 2 x − 1 = 2, (\ displaystyle \ sum _ (n = 0) ^ (\ infty) (\ frac (1) (2 ^ (n))) = \ lim _ (x \ to \ infty) (\ frac (2 ^ (x) - 1) (2 ^ (x-1))) = 2,) </Dd>

What does the sideways figure 8 symbol mean