Why would a merchant in ancient times find it difficult to record "106"bit of grain  bags in a system that lacks a symbol for zero? 
 
What might "106" look like to someone else reading the ledger?
 
Answer:
 
In Hindu Numeral system, zero is used as
 
Without zero, "106" might look like or just a and a with a gap.
It will give reasons for 
 
 
[NOTE: Choose all the answers that might be correct]