How can we make products?
Source: 1981 National High School Mathematics League, Problem 10
February 20, 2020
Problem Statement
To make three kinds of products , we have three parts . A product is made of two and two ; a product is made of one and one ; a product is made of two and one . We have a few parts.
If we make product, product, product, then part and part are remained.
Prove: no matter how we make products, we cannot use up all the parts.