Read the following paragraph and answer the question. Give ONLY the answer, no other words or explanation.

For example:

Answer: <most likely answer, as short as possible>.

Paragraph: 
When energy is released in a chemical reaction or process, that energy is expressed as a negative number. Figure below shows electron affinities in kJ/mol for the main group elements.


Question: How is energy expressed when it is released in a chemical reaction?
as negative number
As a negative number.