Ninths & elevenths
Definition · Level 11 · Interview practice
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For proper fractions: over 9, the numerator repeats (4/9 = 0.444…); over 11, nine times the numerator repeats (3/11 = 0.2727…, 7/11 = 0.6363…).
Example
“Seven over eleven?” — “63.6%.”
Where Tradecraft teaches it
Level 11 · Interview practice, in the lesson “Mental math toolkit”: Near-100 products, squares, fraction tables, compounding, square roots and basis points — the shortcuts behind fast answers.
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