The coins the Vikings had in their possession would have been very different from what we would consider coins. A typical coin of that period might have had a profile of the local ruler and a year of his rule (Year 4 of King Dipshit the Second, that sort of thing.) This would all have been in Latin. These coins were handmade, with a hand-carved die and a piece of gold, silver, or copper pressed into the die and then hit with a hammer. Even better, each batch of coins might have a different mix of gold or silver. When Archimedes had his famous ‘Eureka!’ moment it was because he had figured out how to measure the gold/silver content of precious metals.
Ninth Century Vikings didn’t use coins. It wasn’t until a hundred years later that coins began to be produced in Norway. They used bullion before then, bulk gold or silver. (Grab a bunch of gold cups and plates from a church, that sort of thing.) However, coins were available in England, so they would have been taken on any raids and the Vikings would understand them.
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