Jupyter Notebooks are an interactive, browser-based development environment. They were originally developed to run computation python and as such play very well with numpy. To try numpy in a Jupyter notebook without fully installing either on one's local system Rackspace provides free temporary notebooks at tmpnb.org.
Note: that this is not a proprietary service with any sort of upsells. Jupyter is a wholly open-sourced technology developed by UC Berkeley and Cal Poly San Luis Obispo. Rackspace donates this service as part of the development process.
To try numpy
at tmpnb.org:
Welcome to Python.ipynb
or