Whole numbers are not the only numbers, as we will see in the following chapters. So what does Python do to know if a number is whole? As the language is weakly typed, it must guess. The criterium is simple: in order for a number to be whole, it must not have a decimal point.

Whole numbers in Python

Thus, if one enters

a = 3
print(type(a))
b = 3.14
print(type(b))
c = int(b)
print(c)

one notes that Python knows that a is whole, that b is not, and that c can be whole although it was obtained from b (which is real).

Certain calculations that should give a whole result do not always do so in Python. For example, while ${\sqrt {100}}\in \mathbb {N}$ , Python treats this number as a real number (not a whole number)!

from math import sqrt
a = sqrt(100)
print(a.is_integer())

Operations

Addition, subtraction and multiplication

The first three operations are denoted by the symbols +, - and * as in most programming languages. The sum, difference and product of two (or more) whole numbers are all integers.

a=5
b=-8
print(a+b)
print(a-b)
print(a*b)