In about 3,000 B.C., the Egyptians developed a writing system based on hieroglyphs, or those little pictures drawn on the walls of the pyramids. The Egyptian numeric system was based on ten --- with tenths, hundreds, thousands, ten thousands, and ten million, each having a different picture representing them. While pretty, this system had a number of disadvantages that would make it impractical today.
Requires Much Space
Numbers that were not base ten units were lengthy to write. The number 276, for example involved a total of 15 pictures. Two for the hundreds, 7 for the tenths, and 6 for the ones. This type of notation made for lengthy texts representing simple numbers.
Requires Much Time
You had to draw a picture instead of just a simple symbol. You had to draw multiple symbols for a given number. Paper was in short supply so often you were carving your notations on stone or walls. Often times, wet clay tablets were used that had to harden in the sun. For these reasons, writing Egyptian numerals was very time consuming.
Limiting of Fractions
Egyptian fractions are written the word part over a number that represented the denominator, or bottom part of the fraction. The symbol of a mouth signified the number 1 over the whole, such as 1/5, 1/10 or 1/247. With the exceptions of 2/3 and 3/4, all fractions were limited to having the number 1 in the numerator. The 1 was understood so was not written. You could not write more complicated fractions such as 249/1222, 4/5 or 6/7 in Egyptian numerals.
Difficult to Add
Due to numeric length and character limitations, it was difficult to perform mathematical computations even as simple today as adding fractions in the Egyptian numeric system. To overcome this problem, ancient Egyptians would compose calculation tables to save time and lower the incidence of mathematical error.