For years, Harry Rotenberg had the secret formula for charm and never wrote it down.

He was too busy with his Toronto real estate business and with all the other Harry Rotenberg formulas.

"I'm a formula man," says 73-year-old Rotenberg, who spends his winters at Century Village in Deerfield Beach, Fla. "Everything I do is by formula."

Rotenberg has a formula for staying young, a formula for eating properly, a formula for mass-producing sad songs that could even make a cold man warm.

But even with all those neat formulas, Rotenberg could not have predicted the reaction he would have set off when he recently paid $600 to publish his 32-page pamphlet: "Charm and How to Acquire it."

The Toronto Star did a column on Rotenberg and suddenly newpapers, television and radio reporters from all over wanted to talk to the man who presumed to squeeze the secret of charm in just 32 pages. Instead of being charmed, many people resented Rotenberg for giving them his book. What did he mean by that? Was Rotenberg implying that they weren't charming and needed a book to get charming? A relative threatened to sue.

It started so innocently.

"I had asked myself, 'What is charm? What is it that the stars have that's special?"

The answer came to Rotenberg one night while he was watching the "Late Show". Rudolph Valentino was on. The Shiek was cool, detached, but most important, he was charming.

Suddenly, Harry Rotenberg realized: Nothing matters but dramatic benevolence. This was later revealed in his pamphlet on page 30.

And the key to charm, Rotenberg soon realized was abscence of excitement. "Excitement uses up too much natural energy," Rotenberg says. "You burn it up being excited. You haven't energy left to project charm." If you don't get excited, you have time to be charming.

On page 26, Rotenberg reveals that excitement is the Unknown Factor, Factor X.

That was charm in a nutshell.

Many who knew Rotenberg best were miffed.

"At first," says Rotenberg's wife Charlotte, "I treated this whole thing as a joke. I couldn't get over it, him of all people talking about charm."

Do you consider Harry charming? Charlotte Rotenberg is asked.

"This is off the record," says Rotenberg.

"Shut up," says Charlotte. "No, I don't consider Harry particulary charming."

That's the irony of billing yourself an expert on charm. People get very upset.

"People become very antagonistic," say Rotenberg. "I was nearly crowned by this dame I gave the book to one time. She didn't have charm. She thought she had it, but she didn't."

So Rotenberg learned a trick: "When I give someone a book, I'll write: "To-So-and-So, who doesn't really need a book on charm."

Don't be fooled by Rotenberg's inscription. "Most people overrate their charm content," says Rotenberg. "Fifty percent of the people in this country are below average in charm."

"I don't believe it," says his wife. "Most people have charm."

"There's no other book like this on charm," says Rotenberg.

"What about all those books on how to make friends?" says his wife.

"Those books don't tell you about what charm is," says Rotenberg. "They don't know. Now, for the first time, this information is available."

"Listen to him. He's going to help all the poor people with no charm," says Charlotte. "You know, he once wrote a book on how to grow young and he was giving it out free. I said, 'What are you going to do? Make all of Toronto young at our expense?' Harry was handing it out, and I was working hard to make money."

But it was "Charm and How to Acquire It" that brought Rotenberg fame. The Toronto Star headline said: "You're a Born Loser? Has Harry Got a Book For You!"

During that interview, Rotenberg mentioned a relative, who was unmarried before she read the book. After "Charm," she found a husband, Rotenberg reported. She told Rotenberg if he said that again, she would sue.

Dozens of people came into Rotenberg's Toronto real estate office for the pamphlet.

"The secretary almost quit, she was so swamped," says Charlotte.

Rotenberg got a long distance phone call from Alberta. They put him on a radio talk show.

"I had to shut down the office and take the phone off the hook," says Charlotte.

They called him to lecture in Callgary.

His wife wouldn't let him go. It was too far, she said.

The Toronto subburban Daily Mercury had Rotenberg on the top of the front page. "My nephew called from Montreal. He said, 'Uncle Harry, you made the Montreal Gazette.'"

When they put him on Canadian television, Charlotte closed down the real estate office. All the workers walked down the street to the local television store, where they watched Rotenberg. As he spoke, the station flashed his name every minute: "Harry Rotenberg, Mr. Charm."

During the winter months, Rotenberg can be found around the condominium playing pool, bridge and chess. He exercises regulary. At 73, he can still do 13 pull-ups.

He never snacks and eats at precisely the same time each day. "It gives me a headache," says Charlotte. "I'm out . . . and I have to rush back and feed Harry."

His interests are many. For years he played the violin professionally. He developed a formula for writing sad songs and has had a couple of records pressed.

"I've developed my own musical shorthand," says Rotenberg, "and no one else but me can understand it. See this?"

"Oh that's nothing," says Charlotte. "It's gibberish."

Mike Fiddleman, president of the building where Rotenberg lives, didn't know anything about it.

"Hell, no," says Fiddleman, "he's not charming; all he knows how to do is smile. He's a nice guy, a nice guy.Look, a guy who's a bastard up north is going to be a bastard down here. And a guy who's an a-- up north is going to be an a-- down here.

"Look, as far as Harry being charming, he doesn't say much," says Fiddleman. "We have a building meeting, you ask him about an issue, he says, 'I'm not familiar with anything.' You say, 'Well, what about this, Harry?' He says, 'I'm not familiar with anything.'"

Arthur Ainbinder, a P-Buildidng delegate at Century Village takes the other view: "Harry is extremely charming because he don't interfere. He goes along. He's a good watcher. I'd say he's charming."

By now, Rotenberg is so experienced at talking with reporters, he can suggest headlines for his stories: "'Harry Rotenberg, the Einstien of Personality.' Now that would get people to read it," says Rotenberg.

"I give you everything in this book,"he says. It would be ideal for school children, Rotenberg believes, who are not too young to learn new charming techinques. "It's terrific."

"Harry, that's enough for today," says Charlotte.