In today’s blog, we are going to start a steady and cumulative process of exploring the concepts and techniques of mathematics in an evolutionary way. You will soon realize that even the most basic concepts can be seen in different and interesting ways. As always, and whenever possible, I’ll point you to some interesting places, events and people in the history of mathematics. Lets start with the concept of addition. Addition evolved out of a very fundamental desire to count and know the quantity of similar objects we have.

Suppose we begin with two **sets** of objects **(1)**. Set A consists of six **elements** (blue discs) and Set B has three elements (green discs). These two sets have no elements in common. The **intersection** of sets A and B is the **empty set**. Thus, they are referred to as **disjoint sets**. The **union** of sets A and B consists of both the six blue discs and the three green discs. In the **Hindu/Arabic number system**, there are numbers that are used to represent the quantities of discs in each set **(2)**. In this case, it is the numbers “6” and “3.” The union of two disjointed sets is a visual way of representing the sum of two numbers. The addition symbol (+) is used to represent the operation of addition in a mathematical expression or equation. The sum of these two numbers is equivalent to counting the number of blue and green discs in the union of two sets **(3)**. In this case, six plus three is equal to nine. One should note that **counting** is nothing more than the repeated addition of 1 to generate a set of **natural numbers**.

In 1960, a Belgian geologist, **Jean de Heinzelin de Braucourt** (1920-1998) was exploring an area of Africa near the headwaters of the Nile River at Lake Edwards, called Ishango. At the time, the area was part of the Belgian Congo. He discovered a large number of tools, artifacts, and human remains. In the world of archeology, there have been numerous discoveries of prehistoric animal bones that have notches carved into them. These artifacts are generally known as tallies or tally sticks. Some of these notched bones have proven to be more interesting to the mathematical community than others. One of these interesting bones was discovered at Ishango by Jean de Heinzelin de Braucourt . Today, this artifact is referred to as the **Ishango bone**. It is considered the second oldest mathematical object. However, its exact purpose has yet to be determined.

The Ishango bone is currently on display at the **Royal Institute of Natural Sciences** in Brussels, Belgium. There, you will find a Flash-based website on the Ishango archeological site, which will give you a detailed explanation of the bone’s markings and its possible uses. Explore this site and you will find out how far back the history of mathematics stretches.