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Medium · Mental Math & Estimation · Quant Trader interview question · mental-math, fractions, decimals, arithmetic, probability
In options trading and probability sizing, you often need to convert odds (fractions) into probabilities (decimals) instantaneously to assess edge. While $1/10$ ($0.10$) and $1/2$ ($0.50$) are trivial, prime denominators often trip up candidates. Calculate the decimal expansion of the following fraction: $$\frac{1}{11}$$