Bulgarian banker and trivia-addict Nayden Kostov began writing “Fascinating Facts for the Whole Family” as a solo project until his son, Pavel, asked he could illustrate it.

“I decided ‘why not?’”, Kostov told Delano, adding: “For me, it’s sentimental, I cannot really judge. But feedback from test readers and friends was quite positive.”

The book, which is available in e-book and paperbook via Amazon’s, is Kostov’s third trivia book.

It results from a life-long passion for reading and learning new things. Growing up the son of a school teacher in the Bulgarian countryside, Kostov said he was the first of his siblings to have an obsession with reading. And when he read something he found interesting, it stuck in his memory.

As a young adult, he participated in Bulgaria’s equivalent of “Who Wants to be a Millionaire?”. “I did really well but because of hyper-inflation I didn’t become a millionaire,” he said.

Photo: LaLa La Photo, The latest book was the first time Kostov wrote for younger readers

Kostov spent part of his career working in analysis for the Bulgarian military intelligence before a stint with the European Commission in Brussels and most recently, a bank. But, he never lost track of his taste for trivia, publishing “1123 Hard to Believe Facts”, followed last year by “Which is NOT true?-The Quiz Book”.

The latest book was the first time he wrote for younger readers, as he says “It all starts there. I started being interested in this from an early age.”

In addition to using his son's illustrations, he made sure to benefit from Pavel’s insight for choosing which facts to include. “He was really helpful for this. Also some friends whose kids are the target age read it,” he said.

Pavel, meanwhile, has become something of a celebrity at the European School where he studies. “He showed the book to his teacher and classmates. He was so proud. The classmates asked for his autograph!” Kostov said, adding: “From my perspective as a parent, it makes the book a success.”

And it seems likely this will be the first of a series of family colloborations; Kostov said that his four-year-old son is also keen to illustrate future books.

For information on Kostov’s books and to see pub trivia questions, visit www.raiseyourbrain.com or follow his Facebook page www.facebook.com/raiseyourbrain/