Why are there only ten numbers with single figures?
All numbers are made from ten figures. These are 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9. All decimal numbers are also made from the above ten figures.
Now the question arises, why are there only ten numbers with single figure? Although it cannot be precisely explained, yet some had concluded that this is because ancient people began counting by using their ten fingers. This was easier for them to learn how to handle numbers, as they could use their ten fingers to count.
It is an established fact that right from ancient times, people tried various systems to write numbers. They showed numbers by marking separate indications. For a number like 10 for instance, they showed 10 lines or 10 drawings of birds or animals. This system was used by Egyptians which are still to be found in ancient monuments or structures. In fact, all civilizations have had their own way of writing and using numbers. Romans invented special signs or alphabets for counting. Such signs are called numerals. For centuries, people used Roman numerals. But they are rather clumsy. They did not have zero.
But counting became easier after invention of zero. Zero was invented in 6th century in India and was brought to Europe by Arab travellers at a later stage. Having a figure for zero, any number can be made in a simpler way. It may continue in decimal system. Fractions like 
or 
may be written as decimal fractions like 0.50, 0.25 or 0.75. In fact there are many ways of expressing numbers. In everyday terms numbers are used with units like kg; litre or metre and so on.
It is most interesting to note that computers use a system that use only two digits — 1 and 0. This is called binary system. They play a key role in a modern digital computer. A computer changes numbers and words into codes made up of 0s and 1s. It makes calculation with these codes.
The earliest known written numbers were those used by Babylonians about 5000 years ago. The symbols used today in English for the ten numbers (0, 1, 2,...) are called Arabic or Hindu-Arabic numerals because they came from India through the Arab countries and reached Europe in the 12th century.