Unsupported operand type(s) for *: float and decimal.Decimal

Unsupported operand type(s) for *: float and decimal.Decimal #

The Python "TypeError: unsupported operand type(s) for *: 'float' and 'decimal.Decimal'" occurs when we try to use the multiplication operator with a float and a Decimal object. To solve the error, convert the float to a decimal, e.g. Decimal(my_float) * my_decimal.

Here is an example of how the error occurs.

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from decimal import Decimal


my_float = 3.2
my_decimal = Decimal('3.14')

# ⛔️ TypeError: unsupported operand type(s) for *: 'float' and 'decimal.Decimal'
result = my_float * my_decimal

We are trying to use the division operator with a Decimal object and a float.

Since Decimal objects and floats are handled differently, we have to convert the floating-point number to a Decimal object.

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from decimal import Decimal


my_float = 3.2
my_decimal = Decimal('3.14')

result = Decimal(my_float) * my_decimal

print(result)  # 👉️ 10.04800000000000055777604757

We used the decimal.Decimal class to construct a new Decimal object from a value.

If you call the Decimal class without passing a value, it returns 0.

If you aren't sure what type a variable stores, use the built-in type() class.

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from decimal import Decimal


my_float = 3.2
print(type(my_float))  # 👉️ <class 'float'>
print(isinstance(my_float, float))  # 👉️ True

my_decimal = Decimal('3.14')
print(type(my_decimal))  # 👉️ <class 'decimal.Decimal'>
print(isinstance(my_decimal, Decimal))  # 👉️ True

The type class returns the type of an object.

The isinstance function returns True if the passed in object is an instance or a subclass of the passed in class.

Conclusion #

The Python "TypeError: unsupported operand type(s) for *: 'float' and 'decimal.Decimal'" occurs when we try to use the multiplication operator with a float and a Decimal object. To solve the error, convert the float to a decimal, e.g. Decimal(my_float) * my_decimal.