Tag: number

I solve Python3 practice problems in HackerRank to learn Python coding. I'm stuck on some of the mathematical logic.

Goal: Read an Integer N. Without using any string method, try printing the following: 123 …. N

My approach: I've listed the numbers, found their position position. I've multiplied the numbers with their position value positions (10 ** position value) and summed them to get the desired result. It works for a value of N = 9 where the output is 123456789.

My problem: When N = 10, my mathematical logic fails and the program too! What mathematical logic should I use to deal with the extra digit once N changes by a factor of 10?

My defective python3 code is provided below. Please note that I am asking for mathematical logic and not a python code solution.

Thank you very much.

Deep

"" "
Started on Saturday, October 12 at 00:05:37 2019

@author: deep
"" "

'''
Read an integer N.
Without using any string methods, try to prin the following:
123....N

Example: N=3
output: 123
'''

'''
Not working for N > 9. So N=10 should give an output 12345678910 instead my program gives 123456790. I understand why this is happening as far as coding is concerned but I cannot figure out what mathematical logic I need to employ to tackle to address the additional digit once N changes by a factor of 10
'''

# Creating function to reverse a list
def Reverse(lst)
new_lst = lst(::-1)
return new_lst

# Enter number
N= int(input('Enter a number: '))
Nabs= abs(N)
x=() # List of numbers starting from 0 to N-1
y=() # Reverse of list x()
z=() # List of numbers from 1 to N+1

# Populating list x by appendng with numbers from 0 to N-1.
for i in range(Nabs):
x.append(i)
print(x)

# Length of list
lx=len(x)
print('length: ', lx)

# Creating a reverse list by calling Reverse function for which function has been defined in the beginning of the program. This list will act as the place value calculator as a multiple of 10

y=Reverse(x)
print(y)

# Creating list raning from 1 to N+1 which will act as the list of coefficients that will be multiplied to the elements in the place value list
for j in range(1, Nabs+1):
z.append(j)
print(z)

# Defining parameters: a is used to calculate the product of the coefficients and the place value. b is used to calculate the sum
a=0
b=0

for k in range(lx):
a=z(k)*(10**y(k))
b=b+a

# Negative sign check
if N<0:
b=-b

print(b)
```