Why were the Normans in 1100 considered in Europe not only valiant warriors, but also skilled merchants?

All Norman nobles, being the descendants of the Viking sailors, were equally active in fighting and trading. In the XI century, overseas trade in Western Europe became impossible without knowledge of the Latin alphabet and written account.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.