Calculators to start with were nothing more than an abacus. The first mechanical calculators used levers and typewriter-style buttons to do basic addition and subtraction like Anita Sumlock machines.

These were large in size and used Nixie-tube, Panaplex and VFD displays. The first know scientific calculator was the Hewlett Packard HP-35 calculator, named 35 because it had 35 key functions. This dated to 1972 - 50 years old! It is a handheld sized portable size but with rechargeable battery-pack.

These use a Liquid Crystal Display and needed a lot less power than before so could be made smaller and lighter. Newer types include graphing calculators with full colour display and behaves like a portable computer with apps and countless analytical functions.

Chess originated in India many centuries ago.

The first chess games were played with clay pieces and also with real people.

This type of chess piece set is used widely worldwide in tournament games in competitions.

These have special characters to depict the traditional chessmen are are often made of materials other than wood e.g. stone, resin, metal, porcelain, plastic, bone, ivory[ legal before 1946], horn[legal before 1946], tortoise shell[legal before 1946]

These are modified pieces designed for special purposes when playing chess. The weighted pieces provide extra stability when on a 'shaking' chess board as do magnetic pieces when on a metal based board. The magnetic pieces are also used in many chess computers to provide stability but also in auto-sensory chess computers.

Some chess sets are becoming rare and sought-after, particularly ones over 100 years old and made of  obsolete material.