Teaser 2936: Multicoloured

From The Sunday Times, 30th December 2018 [link]

George and Martha are selling wall-paper of various colours. By replacing letters with positive digits, they have devised the following multiplication problem:

RED × GREY = YELLOW

The N in GREEN is the remaining positive digit. The red wall-paper is sold only in squares, which is appropriate since RED is a perfect square.

What is the value of GREEN?

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