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Pick a Number

This number trick was proposed as a mathematical “sticker” that hosts could share over dessert.

Take a number, multiply it by 5, add 6, multiply by 4, add 9 to the product, multiply the sum by 5, and tell the result. I will tell you your number.

Question: How did the host determine the original number?

Solution:

Source: Leonardo Fibonacci, Italy, 1200