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Calculate the number 1281

NUMBERMANIA: Calculate the number 1281 using numbers [2, 4, 1, 5, 72, 715] and basic arithmetic operations (+, -, *, /). Each of the numbers can be used only once.

Correct answers: 18

The first user who solved this task is Djordje Timotijevic.

#brainteasers #math #numbermania

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Invisible

A psychiatrist's secretary walked into his study and said, "There's a gentleman in the waiting room asking to see you. Claims he's invisible."

The psychiatrist responded, "Tell him I can't see him."

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Florence Seibert

Died 23 Aug 1991 at age 93 (born 6 Oct 1897).American scientist who developed the protein substance used for the tuberculosis skin test, and contributed to safety measures for intravenous drug therapy. In the early 1920s, she discovered that the sudden fevers that sometimes occurred during intravenous injections were caused by bacteria in the distilled water used to make the protein solutions. She invented a distillation apparatus designed to prevent such contamination. In 1941, her improved TB skin test became the standard test in the U.S. and a year later was adopted by the World Health Organization. It is still in use today. Her later research involved the study of bacteria associated with certain cancers.

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