Joan Miles, of Mosgiel, asks :-

Who decided on the numbers 0 to 10?

Garry Tee, a retired mathematician at the University of Auckland, responded.

Most people count sometimes on their ten fingers and some people (as with Inuit) also on their ten toes. People in primitive cultures which might not have spoken words for numbers larger than five commonly answer a question about quantity (such as "how many fish did you catch?") by ticking them off on their fingers and other body parts.

Because of the biological accident that people ordinarily have ten fingers, when people developed words for large quantities they usually named the numbers systematically on a base of ten - such as five hundreds, three tens and seven. But number names based on twenty were used by the ancient Hebrews (as in "three score and ten"), by the Mayans, and by some Europeans until the late 19th century, and some tribes in New Guinea name numbers on base twentyfour.

But civilization (including writing) was invented by the Sumerian people in ancient Iraq, and by the -27th century they had perfected a number system based on sixty, with one written (on clay) as ', ten written as <, AND with a symbol for zero (looking something like Z). Thus, the Sumerian numeral <<''' Z <<<' would be understood as (23 times 60 times 60) + (0 times 60) + 31 (although usually a zero was indicated by a blank space).

In ancient China (-17th century) numbers were written systematically on base ten, with simple symbols for the digits one up to nine and with symbols for tens, hundreds, thousands etc. (which are represented here by X C M). Thus, 2704 was written in a style corresponding to 2M 7C 4, with no symbol for zero being used. In India (by the 7th century) large numbers were being written systematically with ten digits, which were early versions of 0123456789.

And that Indian system is now used worldwide.