Adding subtracting and multiplying were important skills when handling goods such as sacks of grain or heads of cattle in quantities. The Sumerian mathematical system was a hybrid of a sexasgesimal system (in which the basic number is 6 and multiples of 6) and a decimal system based on the number 10 and its multiples).

The Sumerians also developed an efficient system of weights and measures and their supreme invention – that of writing – arose from the practical need to keep records of goods for the purposes of trade, or tax collection.

Those records began in the simplest way with picture images of the item - an ox head for example – and a number of dots to indicate the quantity.

Symbols were drawn on a soft clay tablet using a sharpened reed. The tablet was then baked in a kiln to harden it. Originally list of items were arranged in vertical columns starting from the top right hand side.

**Sumerian numbers and figures**