Die Formel lautet: ${\displaystyle \frac{(a+b)}{2}}\backslash dfrac\{(a+b)\}\{2\}$; also ${\displaystyle \frac{(\text{-}7+5)}{2}}={\displaystyle \frac{\text{-}2}{2}}=\text{ -}1\backslash \; \backslash dfrac\{(\backslash text\{-\}7+5)\}\{2\}\backslash \; =\backslash \; \backslash dfrac\{\backslash text\{-\}2\}\{2\}\backslash \; =\backslash \; \backslash text\{-\}1$

$\text{-}1\backslash text\{-\}\; 1$ liegt in der Mitte der Zahlen $\text{-}7\backslash text\{-\}7$ und $55$.