Add custom row when using select query

So I have a table with name, quantity and price

name        quantity        price        "custom-row"
a           12              5             12*5
b           20              3             20*3
c           18              10            18*10

Is it possible to add a "custom" row when using a select query? And I want the values in that row = quantity * price. How can I do that?

>Solution :

select name, quantity, price, (quantity * price) as custom_row
from table_name

you can just multiply your columns by column name and after AS sign any column name you want