Simplify the following text for a Grade 7 native English-speaking person.
Original: Graham 's number , named after Ronald Graham , is a large number that is an upper bound on the solution to a certain problem in Ramsey theory .
Simplified: Graham 's number is a very , very big number that was discovered by a man called Ronald Graham . It is the answer to a problem in an area of mathematics called Ramsey theory , and is the biggest number ever used in a mathematics study .