If you get following error while importing numpy...

import numpy
ImportError: No module named numpy

Pip Install Numpy

pip install numpy

Above will work for Python2.

Pip3 Install Numpy

If you have Python3 version, do following...

pip3 install numpy

Verify Numpy

In your Python Shell or IDE do...

import numpy

You should not see any error.

Install Anaconda

Best is to to have Anaconda installed. Anaconda is a great package manager to manage Python packages.  Check out following links for installing Anaconda...

Install Anaconda Python On Ubuntu
How to install Anaconda package manager for R and Python
how to install python 3.5 python 3.7 and anaconda on centos

In latest versions of Anaconda, Numpy is installed by default. To check numpy package in Anaconda, run following command...

conda list numpy

You should see output like this...

 conda list numpy
# packages in environment at /home/anaconda3:
# Name                    Version                   Build  Channel
numpy                     1.16.4           py37h7e9f1db_0
numpy-base                1.16.4           py37hde5b4d6_0
numpydoc                  0.9.1                      py_0

If you don't see numpy installed. Then install it using following command...

conda install numpy