Project Euler 5 in Python - How can I optimize my solution?

Question

I\'ve recently been working on Project Euler problems in Python. I am fairly new to Python, and still somewhat new as a programmer.

In any case, I\'ve ran into a sp

Answer 1

How about this? The required number is, after all, the LCM of the given numbers.

def lcm(a,b):
lcm1 = 0
if a == b:
    lcm1 = a
else:
    if a > b:
        greater = a
    else:
        greater = b
    while True:
        if greater % a == 0 and greater % b == 0:
            lcm1 = greater
            break
        greater += 1

return lcm1            


import time
start_time = time.time()

list_numbers = list(range(2,21))

lcm1 = lcm(list_numbers[0],list_numbers[1])

for i in range(2,len(list_numbers)):
    lcm1 = lcm(lcm1,list_numbers[i])

print(lcm1)
print('%0.5f'%(time.time()-start_time))

This code took a full 45 s to get the answer to the actual question! Hope it helps.