sum of first n numbers (natural nos.)

# Using while loop as we don't know the number input
# increasing method 1 + 2 + 3 + 4 + ...
def find_sum(n):
    x = 1 #start with 1
    sum = 0
    while x <= n: #until x reaches the number n
        sum += x
        x +=1
    return sum

# shortcut method using formula
def find_sum(n):
    return n*(n+1)/2

# decreasing method ... + 4 + 3 + 2 + 1
def find_sum(n):
    sum = 0
    while n > 0: # until n reaches 1
        sum +=n
        n -= 1  # decrement of n by 1
    return sum

print(find_sum(15))