Sum-of-squares.md

Sum of squares

The problem

Take a number as input. Then get the sum of the numbers. If the number is n. Then get

0^2+1^2+2^2+3^2+4^2+.............+n^2

Hints

Once again, run a for loop with a range. Inside the loop, use the power of 2. Then add that power to a sum variable. That’s it.

Solution

def square_sum(num) :
    sum = 0
    for i in range(num+1) :
        square = (i ** 2)
        sum = sum + square
    
    return sum

num = int(input('Enter a number: '))
sum = square_sum(num)

print('sum of square numbers is ', sum)

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Explanation

This one is super easy. You declared a variable sum with an initial value 0.

Then you run a for loop. This loop will run for range (num +1).

The reason we are running it until num + 1. Because, we know that the range will stop just before the number inside it.

For example, if we want to run the loop including 10. We should write 11 inside the range function.

If needed, go to the code editor and run the following code.

for i in range(10):
	print(i)

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for i in range(11):
	print(i)

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Shortcut

Sometimes there could be a better and easier way to solve a problem. For example, there is a simple math formula to calculate the sum of the square.

This is the reason, you should search online and learn from different sources. This will make you stronger and better.

If you want to calculate the sum of the square of n numbers, the formula is-

n*(n+1)(2*n+1)/6

Now you can use this formula.

def sum_of_square2(n):
    sum = n*(n+1)*(2*n+1)/6
    return sum

num = int(input('Enter a number: '))
sum = sum_of_square2(num)
print('Your sum of Square is: ', sum)

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Quiz

Why you should learn problem-solving from multiple sources?

1. To utilize the internet bill correctly
2. To learn alternative solutions
3. To pretend that you are busy

Show Answer

The answer is : 2

Take Away

Knowing shortcut ways will make you smarter and faster.

   

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