Python Decimal - Basic usage

The "decimal", which is an instance of Decimal class, is a float-like object in Python.

from decimal import Decimal

d = Decimal(4.5)

print(d)  # 4.5
print(type(d))  # <class 'decimal.Decimal'>

You can input a float or string to the Decimal argument. But the float argument may create an inaccurate object as follows.

from decimal import Decimal

d1 = Decimal('0.1')
d2 = Decimal(0.1)

print(d1)  # 0.1
print(d2)  # 0.1000000000000000055511151231257827021181583404541015625

Arithmetic operations

Decimal numbers can be calculated correctly.

from decimal import Decimal

f = 0.1 * 3

print(f)  # 0.30000000000000004

d = Decimal('0.1') * 3

print(d)  # 0.3

Addition, subtraction, multiplication, division of decimals:

from decimal import Decimal

d1 = Decimal('1.5')
d2 = Decimal('0.6')

print(d1 + d2)  # 2.1
print(d1 - d2)  # 0.9
print(d1 * d2)  # 0.90
print(d1 / d2)  # 2.5

Mix of float and string argument

from decimal import Decimal

print(Decimal(1.5) / Decimal(0.6))  # 2.500000000000000092518585385
print(Decimal('1.5') / Decimal(0.6))  # 2.500000000000000092518585385
print(Decimal(1.5) / Decimal('0.6'))  # 2.5
print(Decimal('1.5') / Decimal('0.6'))  # 2.5