The two streams of Indian classical music, Carnatic music and Hindustani music, have independent sets of rgas. There is some overlap, but more "false friendship" (where rga names overlap, but rga form does not). In north India, the rgas have been primarily categorised into ten thaats or parent scales (by Vishnu Narayan Bhatkhande, 1860-1936); South India uses an older and even more systematic classification scheme called the melakarta classification, with 72 parent (melakarta) rgas. Overall there is a greater identification of rga with scale in the south than in the north, where such an identification is impossible. Rgas in north Indian music system follow the 'law of consonances' established by Bharata in his Natyashastra, which does not tolerate deviation even at the shruti level.

Around 150

Dont know:((
aap yaha ke music expert ko pukariye :))

There can be countless in no. as just wid seven swaraas one can make inumerable ragas out of them.........:-)

There are different types of Ragas.
Sa Re Ga Ma Pa Dha Ni Sa is not a Raga, it is a Sargam which is used to make different Ragas work.
some ragas as follows:
1Bhairav
2Madhyamadi
3Bhairavi
4Bangali
5Varatika
6Madhavi
7Kaushik ...more

Originally, there were six Ragas and thirty-six Raginis (melodies with softer emotions). Hundreds of Ragas were created with the help of these Ragas and Raginis, many of which have become obsolete. In recent times, musicians have composed many more ragas. There are today, approximately, 120-150 ragas in use

Source: http://www.itcsra.org/sra_faq_index.html

8.. i guess