Explain the code it prints 120 how?

Question

b=3
a=1
for i in range(5):
a=a+a*i
print(a)

Answer 1

Initially a = 1
for i = 0
a = 1 + 1 * 0 = 1

Now a = 1
for i = 1
a = 1 + 1 * 1 = 1 + 1 = 2

Now a = 2
for i = 2
a = 2 + 2 * 2 = 2 + 4 = 6

Now a = 6
for i = 3
a = 6 + 6 * 3 = 6 + 18 = 24

Now a = 24
for i = 4
a = 24 + 24 * 4 = 24 + 96 = 120

finally when for loop ends a is 120.

Answer 2

a=1+1*0 #1
a=1+1*1 #2
a=2+2*2 #6
a=6+6*3 #24
a=24+24*4 #120

that's why it prints 120

Answer 3

What does b do?