## Transition to Web3 - Course 2 | Blockchain Basics

Score! The system we designed lets one single true blockchain emerge. Now, let’s dig into the kind of puzzle typically used in blockchain.

For our larger system to work as we described, this puzzle has to be something that:

- inevitably takes time and energy to solve
- lets multiple computers collaborate
- is easy for others to confirm when it is solved

Here is the puzzle that blockchains typically use: “**What additional series of numbers can I add to the block, so that the hash I generate for the whole block starts with X number of zeros? (let’s assume four zeros for now)?**”