Peter is playing dominoes with a standard double six set and begins by laying the double six. He then continues to play dominoes, but in one direction, until he has either exhausted his of 28 dominoes or cant carry on. What will be the number at the end of the last domino?

For a standard double six set domino and starting with a double six,

6|6 followed by 6|5 followed by 5|5 followed by 5|4 followed by 4|4 followed b 4|4 followed by 4|3 followed by 3|3 followed by 3|2 followed by 2|2 followed by 2|1 followed by 1|1 followed by 1|0 followed by 0|0

The last number is 0