Number

You can use integer and floating-point numbers in Python3. For example,

a = 1
b = 2
print(a + b)        # 3
print(b * 3)        # 6
print(1 + 2 * 3)    # 7
print((1 + 2) * 3)  # 9

c = 1.5
print(c * 2)        # 3.0

print(1 / 3)        # 0.3333333333333333
print(1.0 / 3)      # 0.3333333333333333

Converting Numbers to Integer and Floating-Point Numbers:

  • int(x): Converts x to integer
  • float(x): Converts x to floating-point number

Example:

print(int(12.3))    # 12
print(int("234"))   # 234
print(float(12))    # 12.0

Differences Between Python2 and Python3

In Python2:

x = 5 / 2.0         # x = 2.5
x = 5 / 2           # x = 2
x = 5 // 2          # x = 2

In Python3: 

x = 5 / 2.0         # x = 2.5
x = 5 / 2           # x = 2.5
x = 5 // 2          # x = 2

The main difference for the mathematical operations between Python2 and Python3 is 5 / 2. In Python2, single-slash division returns integer divison. This means that the remainder part of the result is discarded. In Python3, single-slash division returns regular division, where the remainder remains a part of the answer.

When you do floor division (5 // 2) or an integer divided by a float (5 / 2.0), the result is the same in both Python 2 and Python3.

Major Change from Python2

The long type in Python has been removed. There are no long-type integers in Python3.

Reference