Known for turning improbable situations into comedy gold with his witty stand-up routines and as the star of two popular TV series from the 1970s and ‘80s, Bob Newhart turns 90 on Sept. 5 (see www.bobnewhartofficial.com).

The former Chicago accountant-turned-comedian suspected he lacked the temperament to remain in the accounting profession back in the mid-1950s when his attitude towards taxation arithmetic could be summed up in three words: “That’s close enough!”

So he and a friend began writing humorous routines based on telephone conversations, which they sold to radio stations.

He eventually dropped the partner but kept the telephone in his act and the one-sided phone conversations have remained throughout his radio, recording, television, and stand-up career. They are as much his trademark as the basset-hound eyes, deadpan delivery, and slightly forced stammer.

Why keep the stammer throughout his career?

“I got my home in Beverly Hills because of that stammer, so I’m not about to drop it now!” he explained during our interview in 2008.

Newhart stormed onto the comedy scene in the 1960s when “The Button-Down Mind of Bob Newhart” became the first comedy record to win a Grammy for Album of the Year with its now classic routines such as ‘Abe Lincoln vs. Madison Avenue.’

He wrote the routine in Chicago when Bill Daily (1927-2018) asked the unknown local comedian to write a piece about press agents. Daily went on to co-star with Newhart and Suzanne Pleshette for five seasons of “The Bob Newhart Show.”

“I couldn’t believe it when I got to work with Bob and Suzanne,” Daily told me in a 2008 interview for Albuquerque Magazine. “Bob is one of the nicest men who ever lived and he’s beyond talented — a comic genius. And what’s amazing is that Bob wasn’t acting on the show — that really was Bob!”

Comedian Elayne Boosler came away with a similar impression when she first met Newhart following a Las Vegas show in the late ‘90s. And at a time when in-your-face, crude comedy is popular, it’s tempting to suggest Newhart’s cleaner style of humor is obsolete. But Boosler disagreed.

“That would be like saying Mozart is outdated,” she told me. “Classics survive. When something has a solid foundation and is so unique and perfect, I don’t think it can ever be outdated. And when you’re the best at something, it just doesn’t go out of style.”

Newhart makes no apologies for his tamer humor, although he could still appreciate more bawdy comedians.

“I even know most of the words they use because I was in the service and they were often directed at me!” he said. “It’s just my choice to work the way I do.”

One of Newhart’s closest friends was fellow funnyman Don Rickles (1926-2017).

“Bob and I are like apples and oranges in terms of our comedy,” Rickles told me in an interview for the Malibu Times in 2008. “But we share the same family values, make each other laugh, and enjoy each other tremendously — he’s brilliant at what he does.”

Newhart delighted in recounting his first encounter with the sharp-tongued comedian in the late 1960s in Las Vegas. The two comedians and their wives met in a cafeteria where Rickles, acting the perfect gentleman, invited Bob and wife Ginnie to his show.

“Don steps out on stage and the first thing out of his mouth is ‘The stammering idiot from Chicago is in the audience today, along with his hooker wife from New Jersey,’” Newhart told me.

But the two families became fast friends and would eventually travel the world together.

In a 2008 interview with the late Dom DeLuise, the comedian recalled working with Newhart in 1964 on the long-forgotten CBS variety show “The Entertainers.”

“It was my first show,” DeLuise told me. “Bob would do his telephone sketches and create magical little stories that were hysterical and he’d hit a bulls-eye every time.”

DeLuise was one of millions of viewers stunned by the 1990 series finale of “Newhart,” Newhart’s second TV series that was set in a Vermont inn.

“Bob woke up from a dream on the set of the original ‘Bob Newhart Show’ with his wife Suzanne Pleshette in bed next to him,” recalled DeLuise. “The entire second series had been a dream! That was just brilliant.”

But Newhart was quick to offer credit. “The whole idea for the ending was Ginnie’s,” he noted.

The episode remains a cherished moment in television history — the type of comic twist that the button-down mind of Bob Newhart has masterfully exploited throughout his 60-year show business career.

Happy birthday Bob!