When you're evaluating -12**2 you're essentially evaluating -(12**2).

And also, (-12) squared is always 144.

If you want to retain the sign use -(12**2). If you don't want the sign to be retained, use (-12)**2

If you're trying to evaluate the square root of a negative number. It is going to be the same as the sqrt of the positive number multiplied by imaginary i

Just evaluate negative numbers the same way you would positive numbers, and append i to it.

In your particular case, the min function is screwing things up when you evalute negative numbers

Perhaps you would accomplish this with something to the effect of

text = raw_input("please give 2 numbers to multiply separated with a comma:")
split_text = text.split(',')
a = int(split_text[0])
b = int(split_text[1])
# The last three lines could be written: a, b = map(int, text.split(','))
# but you may find the code I used a bit easier to understand for now.

if b > 0:
    num_times = b
else:
    num_times = -b

total = 0
# While loops with counters basically should not be used, so I replaced the loop 
# with a for loop. Using a while loop at all is rare.
for i in xrange(num_times):
    total += a 
    # We do this a times, giving us total == a * abs(b)

if b < 0:
    # If b is negative, adjust the total to reflect this.
    total = -total

print total

or maybe

a * b