Questions

The Upanishads are commonly referred to as Vedanta. 

The Upanishads alone are widely known and among the most important literature in the history of Indian religions and culture and their central ideas are at the spiritual core of Hindus.

The upanishads are a part of the Vedas and are ancient Sanskrit texts that contain some of the central philosophical concepts and ideas of Hinduism, some of which are shared with Buddhism, and Jainism.

‘Unless’ is used to denote the condition i.e. ‘If’...... ‘Not’. So, again the use of negative word ‘not’ is superfluous. So, the phrase, ‘are not very’ needs to be replaced with ‘are very’ to make the sentence grammatically correct. Thus, the correct formation would be, ‘Unless, you are very careful, you will run into debt’.

‘Poetry’ needs to be replaced with ‘Poem’ to make the sentence contextually correct. ‘Poetry’ is a literary work; ‘Poem’ is a piece of writing. Here, the writing is being talked about. Thus, the correct sentence would be, ‘The writer of this poem is Wordsworth’.

Bitcoin is the world's first cryptocurrency,    a    form    of electronic   cash.It   is   the    first decentralized digital  currency:  the system   was   designed   to   work without   acentral   bankor   single administrator.Bitcoins    are    sent from  user  to  user  on  the peer-to-peer bitcoin network directly, without the need for intermediaries.  These  transactions are verified by network nodes through cryptography and recorded in a public distributed ledger called a block chain. Bitcoin was invented by an unknown person or group of people   using   the   name Satoshi Nakamoto. Bitcoins are not recognised  as  a  legal  tender  by Reserve Bank of India. 

The second pointer is of char type and not a good pointer.