Add this one to your GRE prep skills.

Gui Guzi, revered military strategist of the Warring States Period, took on two students, Sun Bin and Pang Juan, who developed into formidable warlords in their own right. As a pop quiz, Gui Guzi sat his pupils down and told them to figure out the two numbers between one and ten that he was thinking of.

He whispered the product of the two numbers to Pang, then the sum of the two numbers to Sun.

"Well," admitted Pang, "I don't know the two numbers, but  I wager neither do you, Sun."

"I didn't until you just opened your mouth, " laughed Sun, "but now I do."

"So do I," said Pang. So do we, by the way, as long as the numbers are six and four.

Living in much more turbulent times, Pang and Sun leveraged their logic skills not for college test but battlefield mastery.  Yet Sun proved always the slightly sharper blade. Pang envied his edge, leading to their enmity ,and one of the craftiest battles in history .

Pang left Gui Guzi's tutelage first, to the kingdom of Wei, and rose quickly to command Wei's troops. When Sun departed, he too left for Wei, assuming his old friend would give him a career push. So much for IQ over EQ. Pang advised King Wei that, having ties to the kingdom of Qi, Sun would not prove loyal, and might even be a spy. King Wei ordered Sun Bin's knees crushed, and his face tattooed with a shameful design.

Enslaved to his old schoolmate, Sun had only his wits with which to exact vengeance. He began feigning insanity, gibbering and scampering around doglike on his ruined legs. A wary Pang tested him, placing a great feast before his underfed captive. Pang turned the table over, and dined instead on the animal droppings outside. Convinced his rival was now a harmless madman, Pang began leaving him unattended.

An envoy from Qi encountered Sun in the street, but only a brief conversation convinced the envoy that this ragged creature was a man of uncommon ability. Hearing Sun's plight, the envoy smuggled him under his carriage, out of Wei to Qi.

Cleaned up and restored to dignity, Sun accompanied his new friend to the races. General Tian Ji, supreme commander of Qi's army, was losing sizable sums to other nobles on his horses. Horses raced in three divisions: thoroughbred, not-so-thoroughly bred, and glue pot. No matter which division was racing, General Tian's pony was always out of the money.

Sun edged close to the General and gained his ear. "Follow my strategy and you can bet as heavily as you want," he confided, after a few pleasantries. "Stop matching your horses," he continued. "Put your nag  in the best horse race. Then race your best in the average category and your average horse in the nag race. That way you lose one but win two."

These were the days when officials rewarded good ideas rather than take credit for them, and Sun soon had a position as the King of Qi's strategist. As Chinese history would have it, Pang eventually led the forces of Wei in battle against Qi, besieging Handan city.

The headstrong General Tian Ji was all for meeting the enemy head on. Knowing Pang's troops superior, Sun  advised instead taking the Wei city of Daliang, only lightly defended. A key city, Daliang, once occupied, forced Pang to withdraw his siege. Once again, Sun's mind proved more subtle than that of his nemesis.

Somehow the episode didn't dissuade Pang Juan from trying the same stunt a few years later. Once again, Sun countered by storming Daliang, but first had to reassure General Tian. "He knows we'll do it, but he knows we know he knows. You know?" Whether he knew or not, General Tian gained an identical victory by relying on Sun's chess.

After the withdrawal, though, Pang decided to force an encounter with the Qi army. Although more evenly matched this time, Sun had the troops retreat in all haste. A pursuing Pang found empty camps with fewer and fewer cooking fires, and surmised that the Qi troops were losing heart and deserting. He gathered 10,000 of his best forces and chased headlong into the narrow valley of Malin.

They found the far end barricaded by fallen trees, a cunning ploy to hold them back, yet easily enough removed. Not until nightfall did his soldiers come to the last trees, and one which had had its bark scraped off.

"Someone's written on it in charcoal," reported a soldier.

"Give me a torch!" commanded Pang.

The light revealed characters which read, "Pang Juan will die under this tree."

"Damn that tattooed-faced scoundrel!" barked Pang, as the first arrow pierced his chest. Sun's archers were perched in the valley heights, raining death on the outfoxed Wei  troops.

"I've fallen victim to that clever dog at last," moaned Pang. Before the arrow could do its work, Pang drew his sword and slit his own throat with it.  The vanguard was obliterated, the army captured, and Sun elevated to demigod status.  Thus does a classic tale of brains, betrayal, and redemption languish in CCTV's portfolio, rather than being rightfully developed into a blockbuster starring Jet Li and Jackie Chan.