IF Donald LaPlace, New York’s oddsmaker, is on the money, as he usually is, thousands of Americans are going to plunge millions of dollars on a recent maiden graduate to win Saturday’s Belmont Stakes.

Has the world gone crazy or are they on to something?

LaPlace has made this unlikely horse, Aptitude, the 8-5 favorite on the morning line to whip 10 rivals over the mile-and-a-half marathon.

When LaPlace told trainer Bobby Frankel he had made Aptitude the short-priced chalk, Bobby cringed and cried, “God, you’re putting the pressure on me. Couldn’t you have at least made him 2-1?”

Don’t worry about pressure on Frankel, known in his younger years around here as Broadway Bobby before he moved to California and became Hollywood Bobby. He’s won enough and accomplished enough to take anything.

It’s the horse who is going to feel the pressure, as he storms through the stretch attempting to win the Belmont from at least 10 lengths out of it.

Aptitude has had just six starts, from which he has won only one race, a modest maiden around two turns at Santa Anita on Jan. 1. That’s it, folks. Yet the public is going to dump a small fortune on his nose to win one of the toughest, greatest and most prestigious horse races in the world on Saturday.

No wonder Bobby is sweating. When the public piles it on your horse at the windows, and the whole world is watching, you better deliver – or run for the exits.

Aptitude is favorite for two reasons. There isn’t a single Grade 1 winner in the Belmont, which means that although Aptitude’s chart is paper thin, his rivals might be even thinner.

And he comes to the Belmont off a terrific second to Fusaichi Pegasus in the Kentucky Derby. He was beaten only a length and a half for all the money after coming from 14th in a field of 19.

The moment he crossed the line, Frankel scrubbed the Preakness and took dead aim at the Belmont “because Aptitude has Belmont stamped all over him.”

That means Aptitude has Belmont breeding from top to bottom – the sire is A.P. Indy, the 1992 Belmont winner, the dam is by Northern Dancer, the sire of all sires – he has the look of a stayer and he runs like a stayer.

Candidly, Frankel’s credentials far exceed those of his horse. He is extremely astute, a Hall of Famer whose feats on both coasts are too numerous even to begin canvassing.

So when he fires a sharp Derby horse, then ships him in to New York as the Belmont favorite after a five-week freshening in California, he may well have the goods.

Bobby doesn’t give a whit about the Belmont’s pace set-up, which is shy of real, contested speed to suit Aptitude’s late closing rush. “The best horse will win the Belmont no matter what the pace,” he said yesterday. “You go a mile and a half and no one is going to steal it and no one is going to lose it from behind if they’re good enough.”

He insists that Aptitude should have won the Gotham at Aqueduct in March and he adds, “The sheets guys (who measure horse performances in figures) say we ran the same number as Fusaichi Pegasus in the Derby. Although we were beaten a length and a half, we had the wider trip.”

Frankel exudes confidence. “I wouldn’t be here if I didn’t think I could win,” he said.

Frankel concedes it will be easier to win the Belmont without the Derby and Preakness winners in the field – and he’s not losing any sleep over their absence. “The less competition the better,” he said. “I wish it was a walkover.”

There is a precision about Frankel’s handling of Aptitude that is reassuring for his admirers. He didn’t give the Preakness a thought because this was his “Belmont horse.” He said, “Of the three Triple Crown races, I believed from the start that the Belmont would be our best chance to win.”

And the horse has done nothing since to change his mind. “He’s in great shape,” he said. “He never gives up. He is always trying to the end.”

Another who likes Aptitude is Angel Cordero Jr., the old saddle maestro, coming off a big win himself over the weekend when he wangled his jockey John Velazquez onto Running Stag to win the rich Mass. Handicap.

“I love Bobby’s horse,” said Angel. “The way he ran against Red Bullet in the Wood Memorial and against Fusaichi Pegasus in the Derby he’s got a real good chance.”

He rates Impeachment and Wheelaway the dangers. “I think Impeachment, with his closing style, is going to like the distance and Wheelaway ran a great race in the Derby.”