Yh I don't know where they get these numbers from, in the asian culture its usually elders who tell so and so to pray a certain name of Allah 100x, 5000x. I've not read anything about it from the sunnah.
True.

sister,
Yes we people (and I don't mean just you sister, many of us) are of the opinion that if somethings happened and we want Allah to help us, we must read x thing 100 times and Y name of Allah's another 100 times etc.
I don't know why, but we seem to be afraid of, or think that we can't, talk to Allah and ask of Him. He is our Creator, our Protecting Helper, the Hearer of our Du'as and the Remover of our troubles. So why can't we talk to Him and have a straight conversation with Him?
What we have been taught in the sunnah, and in the Qur'an is to make du'a.
A means of having one's du'a accepted, is by mentioning the dire circumstances that one is in, and the desperate need that one has for Allah's Mercy and Blessings E.g. in Surah Maryam, ayah 4, Zakariyya alaihissalaam starts his du'a for a son by mentioning the state that he is in of old age, and how he needs a son, for he might be on the verge of death. Nuh alaissalaam, when he was rejected by his own people, cried out, "Annee maghloobun fantasir! I have been overpowered, so help me!" (Surah al-Qamar, ayah 10). So he mentioned the appalling circumstances that he was in - that he had been overpowered by his enemies - and used that in the du'a to increase the chances of his du'a being responded to. Likewise, when Musa was alone in the valley of Midyan, with no supporter or helper, he cried to Allah, "Rabbi innee limaa anzalta ilayya min khayrin faqeer! O my Lord! Verily I am faqir (needy) for whatever good that you can send down upon me."(Surah al-Qasas, ayah 24).
This is even used amongst people. E.g. doesn't a beggar, when he stands up to ask for money, announce, "I am a person with a large family, and I have many debts to pay back, and cannot find work...?" All of this is used in order for him to obtain more sympathy from the people that hear him, and indeed to Allah belongs the greatest example.
Imagine if the beggar doesn't tell people his situation, doesn't tell them what he needs, but just says, "o people, o people, o people,..." (100 times). It's not going to work as well is it?
We can ask Allah by His names and attributes, eg O Allah, I ask You by Your being the One and Only God, and by Your being the Hearer of du'as and Bestower of blessings, Remover of Troubles, that you remove xyz trouble from me, and grant me blessings etc.
What you describe is not from the sunnah, as far as I know. Why not make du'a as taught by the Prophet :saws:, and as was the way of all the former Prophets (alayhim assalaam)? Isn't that the best way?
And Allah knows best.
