I am unable to install web3 on my mac

This is a Node question more so.

But most likely your issues lies here:

no such file or directory, open '/Users/saitejakuruva/package.json'

You're not in a proper project directly when calling npm install. NPM was trying to write to, or update, the package.json file.

Try npm install -g web3 which will install web3 at a global level available to all projects.

This may go against best practices elsewhere per project, so be aware.

Update:

Link to fixing permission issues with Mac and NPM: https://stackoverflow.com/questions/47252451/permission-denied-when-installing-npm-modules-in-osx/47252840