## Hash Value

The blockchain transaction hash value is hexadecimal.

**Hexadecimal** (or hex) is a base 16 system used to simplify how binary is represented. A hex digit can be any of the following 16 digits: 0 1 2 3 4 5 6 7 8 9 A B C D E F. Each hex digit reflects a 4-bit binary sequence.

## Decide a Card

We decide a card by 2 hex digits.

One digit represent the Rank of the card, that's among 13 values:

Ace (1), 2, 3 , 4 , 5 , 6, 7 , 8, 9 , 10(a), Jack (b), Queen (c), King (d)

Another digit represent the Color of the card, that's among 4 values:

Heart, Diamond, Club, Spade