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# Sum of Square Series

In this post I will show you how to write a Python program to calculate sum of series 1²+2²+3²+….+n².

The following is the mathematical formula for Sum of series:

 1²+2²+3²+….+n² = ( n (n+1) (2n+1)) / 6.

# #Program to calculate sum of series 1²+2²+3²+….+n² by using the above formula.

```num = int(input("Enter any Positive Number  : "))

sum = 0

sum = (num * (num + 1) * (2 * num + 1)) / 6

print("The Sum of Series upto {0}  = {1}".format(num, sum))
```

Output

 Enter any Positive Number  : 7 The Sum of Series upto 7  = 140.0

Calculation

 num=7 sum = (num * (num + 1) * (2 * num + 1)) / 6 sum=(7 * (7 + 1) * (2 * 7 +1)) / 6 sum=140.0

# Program to calculate Sum of Series 1²+2²+3²+….+n² for loop.

```num = int(input("Enter any Positive Number  : "))
sum = 0
sum = (num * (num + 1) * (2 * num + 1)) / 6
for i in range(1, num + 1):
if(i != num):
print("%d^2 + " %i, end = ' ')
else:
print("{0}^2 = {1}".format(i, sum))

```

Output

 Enter any Positive Number  : 7 1^2 +  2^2 +  3^2 +  4^2 +  5^2 +  6^2 +  7^2 = 140.0

#Python Program to calculate Sum of Series 1²+2²+3²+….+n² using functions

```def sum_of_square_series(num):
sum=0
sum = (num * (num + 1) * (2 * num + 1)) / 6
for i in range(1, num + 1):
if(i != num):
print("%d^2 + " %i, end = ' ')
else:
print("{0}^2 = {1}".format(i, sum))
N= int(input("Enter any Positive Number  : "))
sum_of_square_series(N)

```

Output

 Enter any Positive Number  : 7 1^2 +  2^2 +  3^2 +  4^2 +  5^2 +  6^2 +  7^2 = 140.0

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