One Day a Jewish person came to Imam Ali (AS), thinking that since Imam Ali thinks he is too smart, I'll ask him such a tough question that he won't be able to answer it and I'll have the chance to embarrass him in front of all the Arabs.
He asked "Imam Ali, tell me a number, that if we divide it by any number from 1-10 the answer will always come in the form of a whole number and not as a fraction."
Imam Ali (AS) looked back at him and said, "Take the number of days in a year and multiply it with the number of days in a week and you will have your answer."
The Jewish person got astonished but as he was a polytheist (Mushrik), he still didn't believe Imam Ali ibn Abu Talib (AS) He calculated the answer Imam Ali ibn Abu Talib (AS) gave him.
To his amazement he came across the following results:
source : sibtayn
