A shop sells sweets in bags of 7 and 20 what is the largest number of sweets that cannot be purchased exactly?

Question

Mathematics

Jaxson

13 February, 13:09

A shop sells sweets in bags of 7 and 20 what is the largest number of sweets that cannot be purchased exactly?

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Answers (1)

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Murray · Answer 1

By the Frobenius Coin Theorem, also known as the Postage Stamp Theorem or the Chicken McNugget Theorem, the maximum amount that cannot be represented as a sum of multiples of two relatively prime numbers a and b (numbers that have GCF of 1) is ab-a-b. Plugging 7 and 20 in, our answer is 7*20-7-20, or 140-27, or 113.