What does « Hundred » mean in the Quran?

Or [consider such an example] as the one who passed by a township which had fallen into ruin. He said, "How will Allah bring this to life after its death?" So Allah caused him to die for a hundred years; then He revived him. He said, "How long have you remained?" The man said, "I have remained a day or part of a day." He said, "Rather, you have remained one hundred years. Look at your food and your drink; it has not changed with time. And look at your donkey; and We will make you a sign for the people. And look at the bones [of this donkey] - how We raise them and then We cover them with flesh." And when it became clear to him, he said, "I know that Allah is over all things competent."

The example of those who spend their wealth in the way of Allah is like a seed [of grain] which grows seven spikes; in each spike is a hundred grains. And Allah multiplies [His reward] for whom He wills. And Allah is all-Encompassing and Knowing.

O Prophet, urge the believers to battle. If there are among you twenty [who are] steadfast, they will overcome two hundred. And if there are among you one hundred [who are] steadfast, they will overcome a thousand of those who have disbelieved because they are a people who do not understand.

Now, Allah has lightened [the hardship] for you, and He knows that among you is weakness. So if there are from you one hundred [who are] steadfast, they will overcome two hundred. And if there are among you a thousand, they will overcome two thousand by permission of Allah. And Allah is with the steadfast.

And they remained in their cave for three hundred years and exceeded by nine.