One of the most often used, and often disagreed upon, scuba hand signs is numbers. The following hand signals are used by cave divers and
other technical divers because it can be implemented with one hand. In addition, these signs work as an alphabet, and does not require addition
or counting of subsequent signs.
Cave Diving/Technical Diving
Each hand signal is a number. In the above example, 1 +8 +0 +0 = 1800.
Some teams prefer to omit the last zero signals, since hundreds can be implied. Especially if the 'question'+'gauge'signal was used to
ask the team's pressure.
OW/Two Handed
Each finger is 100, and the signals are totalled together. In the above example, 1000 + 800 = 1800.
Counting 5's
Each finger is 100, and the signals are arithmetically summed In the above example, 500 + 500 + 500 +300 = 1800.
Images courtesy Deep-Sea Sherpa

Without Animals there is no Paradise