# CodeSkulptor3 (Probability Plot) Aug 2020

I built a short presentation demonstrating the use of CodeSkulptor3 (Python 3).

This time, my goal was to illustrate coding a small probability problem including a plot of results — accessible from any device — desktop, phone, iPad.
CodeSkulptor3 is a free Python language 'sandbox' for messing around with simple programs

Probability of finding exactly one digit “7” in the range of numbers from 0 to 10^x exclusive

Example 1:

probability in the range of numbers from 0 to 9 (all one-digit numbers)= 0.10


Example 2:

probability in the range of numbers from 0 to 99 (all two-digit numbers)= 0.18
[7, 17, 27, 37, 47, 57, 67, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 87, 97]

Code Text

Copy the code below
Paste it into CodeSkulptor3.
and press the run button
```
```
# digit we are trying to match
match = '7'

# my_maxes will be a list from 10 to 10^30
# my_maxes = [10, 100, 1000 ... ]
my_exponents = range(31)
my_maxes = [10**k for k in my_exponents]

# verify
print(my_exponents)
print(my_maxes)

xs = [e for e in my_exponents]
ys = []

for exponent in my_exponents:
ans = (exponent)*9**(exponent-1)
possible = 10**exponent
ratio = exponent/10*0.9**(exponent-1)
#print(possible, ans, ans/possible)
ys.append(ratio)
print(exponent, possible, ans, ratio)

print("\n---")

import simpleplot

# verify
print(xs)
print(ys)

dataset = list(zip(xs,ys))

# verify
print(dataset)

# pops up a line plot
simpleplot.plot_lines('My Answer', 400, 300, 'exponent of 10', 'probability', [dataset], True)
```
```