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When a solute distributes between two immiscible solvents: K = C(organic)/C(aqueous) = constant at given temperature. If K > 1, compound prefers organic phase → extraction is favorable. Single extraction with V mL organic solvent from W mL water with initial mass m: mass extracted = mKV/(W + KV). Remaining = mW/(W + KV). Multiple extractions (n times with V/n mL each): remaining after n extractions = m[W/(W + KV/n)]^n. Mathematical proof: [W/(W + KV/n)]^n < W/(W + KV) for n > 1. Therefore multiple small extractions ALWAYS recover more than one large extraction. Practical example: K = 4, 10 g compound in 100 mL water. One extraction with 100 mL ether: extracted = 10(4)(100)/(100+400) = 8 g (80%). Three extractions with 33.3 mL each: first removes ~5.7 g, second ~2.4 g, third ~1.0 g → total ~9.1 g (91%). Significant improvement with same total solvent. JEE calculations: set up K equation, solve for mass extracted, compare single vs multiple extractions. Always show that n extractions are more efficient.