To make sure a string will display as expected, we can format the result with 
the format() method.
The format() method allows you to format selected parts of a string.
Sometimes there are parts of a text that you do not control, maybe they come from a database, or user input?
To control such values, 
add placeholders (curly brackets {}) in the text, and run the values through the 
format() method:
Add a placeholder where you want to display the price:
  price = 49
txt = "The price is {} dollars"
print(txt.format(price))
You can add parameters inside the curly brackets to specify how to convert the value:
Format the price to be displayed as a number with two decimals:
  txt = "The price is {:.2f} dollars"
If you want to use more values, just add more values to the format() method:
print(txt.format(price, itemno, count))
And add more placeholders:
  quantity = 3
itemno = 567
price = 49
myorder = "I want {} pieces of 
  item number {} for {:.2f} dollars."
print(myorder.format(quantity, itemno, price))
You can use index numbers (a number inside the curly brackets {0}) to be sure the 
values are placed 
in the correct placeholders:
  quantity = 3
itemno = 567
price = 49
myorder = "I want {0} pieces of 
  item number {1} for {2:.2f} dollars."
print(myorder.format(quantity, itemno, price))
Also, if you want to refer to the same value more than once, use the index number:
  age = 36
name = "John"
txt = "His name is {1}. {1} is {0} years old."
print(txt.format(age, 
  name))
You can also use named indexes by entering a name inside the curly brackets {carname}, 
but then you must use names when you pass the parameter values
txt.format(carname = "Ford"):
  myorder = "I have a {carname}, it is a {model}."
print(myorder.format(carname 
  = "Ford", model = "Mustang"))