To throw a Christmas party for 500 energetic and single-minded children and send everyone home happy is no simple trick, but the Prince George's County police know how.

Their secret? Volume.

For example: They did not have just one Santa Claus on hand to field the requests of youngsters at their second annual community party for underprivileged children held at Central High School near Capitol Heights yesterday. They had six.

"We wanted each child to have a chance to sit and talk with Santa Claus," explained police spokesman Capt. David B. Mitchell. "With this many kids you have to break it down."

At the end of the day, when the food was gone and the entertainment was over, the police had achieved the contentedness of letting each youngster clench his or her fist around a bag full of holiday gifts.

The immediate reason for the holiday bash, Police Chief Michael J. Flaherty said yesterday, was nothing other than to give a good time to children who deserved it. Deserving children were selected by guidance counselors at Prince George's 115 public elementary schools.

But Flaherty said that police hope a long-term payoff will come in the form of improved relations with youths who often associate the police with trouble only.

"The children get to celebrate with police officers, and they get to know them as people," Flaherty said. "I think that goes a long way."

"Children might be suspicious of the police, because the only way they see him is when something bad has happened . . . . This is different," agreed Cora Rice, a Prince George's community leader and an organizer of yesterday's party.

Police were pleased by the squeals of delight that rang from Central's auditorium when magician Arty Freda took the stage.

Children seemed slightly less enthusiastic by the round of Christmas caroling that came later. "What's happening out there?" asked Mary McCord as she attempted to lead the children through a version of "Deck the Halls." "I'm not hearing you."

McCord had better luck with "Jingle Bells," but that late in the afternoon, singing of any kind was going to be an uphill climb. The children had refined their concentration to a single subject: presents.

"That was the best part -- the presents," said 11-year-old LaShawn Scott as she headed for a bus home at party's end. "I liked the magic too."

The cost of the presents, like the rest of the $9,000 party, was covered by community donations, Mitchell said.

Yesterday's festive spirit was not reserved to the children in attendance.

"The officers have a great time too. It gives them a chance to interact with children," said Flaherty, who was wearing a bright orange button declaring: "I Hugged a Clown Today."

"I kissed her too. That's how I got rouge all over my face," Flaherty said.

But there was probably no one as happy to be at yesterday's party as 6-year-old Cory Teams. Last year, Prince George's police gave Cory a party of his own, because at the time he was suffering from what had been called terminal cancer. Unexpectedly, the cancer later went into remission, so Cory was at the party yesterday with his mother, Debra Teams.

To Rice, Cory's improved health provides a special lesson for the holidays: "We feel that our party gave him the courage to get better because he knew that people really cared."