most people just using bitcoin for investation
don't know how exactly number of people using bitcoin 

I think the number is higher than just 100 a day.. Maybe at around 500 per day is more correct. We are growing faster with every new user, because they will talk to others about it and their friends will talk to their friends too and so on, making the community grow faster than we think.

The easiest thing to calculate the actual user data is of the bitcoin wallet. I'm very sure that all transactions are recorded in the wallets.

i think bitcoins value is not basing on gold. the developers has their own way to make the value of it plus the demand of the users for the bitcoin. the volume of the bitcoin also changes its value. we cant really calculate the number of users of bitcoin today because we dont have any ideas on how to calculate it because bitcoin users can make multiple accounts this days.

just what other says. we cannot calculate the exact number of users of bitcoin for today. but in the near future when the developers of bitcoin has added some features about the security of bitcoin accounts. there would be way for it to calculate the exact number of users in the whole world.

That is true for sure but does it help at all? We can get the number of bitcoin wallets ever used and then divide that to the average number of bitcoin wallet bitcoin users has. That's an easy way to go but we don't even know the average number of bitcoin wallet an individual bitcoin user has. It's another problem to solve. And even if we have the average number of bitcoin wallet per individual, someone can make the record false in just a couple of hours by making tons of wallet that all belongs to him.

The amount of bitcoin wallets just don't help at all since you can create infinite number of them.

yeah i also never focus on the actual number of bitcoin users i just using bitcoin and trade in bitcoin and i use some bitcoin for online shopping because its very easy to use in anywhere for online shopping.

That is right. But we can estimate from the number of transactions.

I don't think who can measure all of the people using bitcoins as everyday there and there is a new bitcoiners .Some said it is near on the total counts of accounts in blockchain .But it is not so sure because not all users use blockchain and some of the blockchain wallets are not active .One person can create multiple blockchain wallets. Instead of counting the people who use bitcoins it is much better to share our ideas to other people about bitcoins that have make more sense . 

You cant get an accurate number of how many people use the Bitcoin.
Because some people have more than one Bitcoin account