doubling a number

[perfringo]

Maybe some simple doubling function?

def double(text):
    doubled = []
    carry = 0
    for num in text[::-1]:
        if num in ('.', ','):
            doubled.append(num)
        else:
            quotient, reminder = divmod(2 * int(num), 10)
            doubled.append(str(reminder+carry))
            carry = quotient
    if carry:
        doubled.append(str(carry))

    return ''.join(doubled[::-1])


for num in ("1", "10", "12.5", "1.9", "99", "99.7899", "99.999"):
    print(f"{num}, {double(num)}")

1, 2
10, 20
12.5, 25.0
1.9, 3.8
99, 198
99.7899, 199.5798
99.999, 199.998