Sorry for the copy & paste job ..but this is one of the funniest passages I have read (Swami and Friends-R.K.Narayan)

Half an hour later Swaminathan sat in his father's room in a chair, with a slate in his hand and pencil ready. Father held the arithmetic book open and dictated, "Rama has ten mangoes with which he wants to earn fifteen annas. Krishna wants only four mangoes. How much will Krishna have to pay?"

Swaminathan gazed and gazed at this sum, and every time he read it, it seemed to acquire a new meaning. He had the feeling of having stepped into a fearful maze...

His mouth began to water at the thought of mangoes. He wondered what made Rama fix fifteen annas for ten mangoes. What kind of a man was Rama? Probably he was like Sankar. Somehow one couldn't help feeling that he must have been like Sankar, with his ten mangoes and his iron determination to get fifteen annas. If Rama was like Sankar, Krishna must have been like the Pea. Here Swaminathan felt an unaccountable sympathy for Krishna.

"Have you done the sum?", father asked, looking over the newspaper he was reading.

"Father, will you tell me if the mangoes were ripe?"

Father regarded him for a while and smothering a smile remarked: "Do the sum first. I will tell you whether the fruits were ripe or not, afterwards"

Swaminathan felt utterly helpless. If only father would tell him whether Rama was trying to sell ripe fruits or unripe ones! Of what avail would it be to tell him afterwards? He felt strongly that the answer to this question contained the key to the whole problem. It would be scandalous to expect fifteen annas for ten unripe mangoes. But even if he did, it wouldn't be unlike Rama, whom Swaminathan was steadily beginning to hate and invest with the darkest qualities.

"Father, I cannot do the sum", Swaminathan said, pushing away the slate.

"What is the matter with you? You can't solve a simple problem in Simple Proportion?"

"We are not taught this kind of thing in our school"

"Get the slate here. I will make you give the answer now" Swaminathan waited with interest for the miracle to happen. Father studied the sum for a second and asked: "What is the price of ten mangoes?"

Swaminathan looked over the sum to find out which part of the sum contained an answer to this question. "I don't know"

"You seem to be an extraordinary idiot. Now read the sum. Come on. How much does Rama expect for ten mangoes?"

"Fifteen annas of course", Swaminathan thought, but how could that be its price, just price? It was very well for Rama to expect it in his avarice. But was it the right price? And then there was the obscure point whether the mangoes were ripe or not. If they were ripe, fifteen annas might not be an improbable price. If only he could get more light on this point!

"How much does Rama want for his mangoes?"

"Fifteen annas" replied Swaminathan without conviction.

"Very good. How many mangoes does Krishna want?"

"Four"

"What is the price of four?"

Father seemed to delight in torturing him. How could he know? How could he know what that fool Krishna would pay?

"Look here, boy. I have half a mind to thrash you. What have you in your head? Ten mangoes cost fifteen annas. What is the price of one? Come on. If you don't say it--" His hand took Swaminathan's ear and gently twisted it. Swaminathan could not open his mouth because he could not decide whether the solution lay in the realm of addition, subtraction, multiplication, or division. The longer he hesitated, the more violent the twist was becoming. In the end when father was waiting with a scowl for an answer, he received only a squeal from his son. "I am not going to leave you till you tell me how much a single mango costs at fifteen annas for ten" What was the matter with father? Swaminathan kept blinking. Where was the urgency to know its price? Anyway, if father wanted so badly to know, instead of harassing him, let him go to the market and find it out. The whole brood of Ramas and Krishnas, with their endless transactions with odd quantities of mangoes and fractions of money, were getting disgusting.

Father admitted defeat by declaring: "One mango costs fifteen over ten annas. Simplify it"

Here he was being led to the most hideous regions of arithmetic, Fractions. "Give me the slate, father. I will find it out"

He worked and found at the end of fifteen minutes: "The price of one mango is three over two annaas" He expected to be contradicted any moment. But father said: "Very good, simplify it further"

It was plain sailing after that. Swaminathan announced at the end of half an hour's agony: "Krishna must pay six annas" and burst into tears.