This was done to show the power of cloud computing.
"A Yahoo! engineer has reached a new cloud computing milestone. Using Hadoop, Yahoo! cloud computing engineer, Tsz Wo (Nicholas) Sze has determined the computation of π (pi) to the two quadrillionth decimal. And it equals zero. It's the most amount of bits ever calculated for pi.
This is a remarkable achievement and shows the power of distributed systems for crunching big data.
It's also an example of how data is changing our infrastructure as we discover new ways to develop applications with greater computational capabilities."