What does sigma mean I maths
Hello, baxteryay!
This is based on a classic problem.
Answer: his chain had from 8 to 15 links.
Suppose his chain had 7 links.
He could cut one link like this: .$\displaystyle \subset\!\supset\!\!\!\subset\!\!\supset \;\;\subset\!\supset \;\;\subset\!\!\supset \!\!\!\subset\!\supset \!\!\! \subset\!\supset \!\!\!\subset\!\supset $
Then he can present from 1 to 7 links.
. . $\displaystyle \begin{array}{cc} \text{Number} & \text{Combination} \\ \hline 1 & 1 \\ 2 & 2 \\ 3 & 1+2 \\ 4 & 4 \\ 5 & 1+4 \\ 6 & 2+4 \\ 7 & 1+2+4 \end{array}$
Since he needed two cuts, he had more than 7 links,
. . up to a maximum of 15 links.
Suppose his chain had 15 links.
Again, he would cut the 3rd link . . . and cut the 7th link.
This gives him four chains with 2, 1, 4, and 8 links.
Then he can present from 1 to 15 links.