When you or someone you are caring for is seriously ill, it is recommend that you keep EOBs for five years after the illness or condition is alleviated. If you or the patient is claiming or has claimed a medical deduction, keep the explanation of benefits for seven years.
The earliest writing can be traced to Sumer, in Mesopotamia. This system did not use an alphabet, instead it used pictographs which are symbols representing familiar objects. This type of writing was called cuneiform, or wedge-shaped writing. Egyptians used hieroglyphics, also a pictograph system.
See History of writing ancient numbers for how the writing of numbers began. It is generally agreed that true writing of language (not only numbers) was invented independently in at least two places: Mesopotamia (specifically, ancient Sumer) around 3200 BC and Mesoamerica around 600 BC. Several Mesoamerican scripts are known, the oldest being from the Olmec or Zapotec of Mexico.