ModuleNotFoundError: No module named 'numpy'

[InvaderDolan]

After downloading, extracting and just simply starting the program I get an error:
~/Documents/CSGO-HLTV-Simulation-master$ python3 simulation.py
Traceback (most recent call last):
File "simulation.py", line 23, in
from simulationFunctions import *
File "/home/invader/Documents/CSGO-HLTV-Simulation-master/simulationFunctions.py", line 18, in
import numpy # Using nextafter() function
ModuleNotFoundError: No module named 'numpy'