L3

"Sing a song of sixpence" has embedded in it old references to base 12 (sixpence), old grains (rye), old ways of stating numbers (four and twenty), other things parlour, maid, hanging out washing. NB "counting house" too.

L2. Very early devices

The antikythetra
The abacus.

<iframe width="1280" height="720" src="https://www.youtube.com/embed/RyBsOe6E_aI" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>
'
Why have numbers? The one-one correspondance.
Tally Marks

Bones

 It is the oldest attestation of the practice of arithmetic in human history. 

L1 Numbers

Numbers.

Lectures

L1.
Numbers

L2
Very early devices. Abacus, antikythera.

L3. Middle ages up to Charles Babbage.

L4 Charles Babbage and computers up to WWII

L5 The rise of the micro.

L6 The future.