一个简单python小事情

碰到这个情况该怎么办，确实有点难住我了。具体的操作是什么样子的

def fac(n):
    if n == 1:
        return 1
    return fac(n-1)*n

e = 1
case = 1
i = 1
while case >= (1/10**6):
    case = 1/fac(i)
    e+=case
    i+=1
print(e)

第一个

def isprime(n):
    if n == 1:
        return False
    elif n == 2:
        return True
    for i in range(2,n):
        if n%i == 0:
            return False
    return True

ls = []
for i in range(100,1000):
    if isprime(i) and isprime(i+2):
        ls.append((i,i+2))
for i in range(len(ls)):
    print(ls[i],end=  "\t")
    if (i+1)%5 == 0:
        print("",end = "\n")