MongoDB $multiply

Multiply two or more numeric values.

Operands can be field paths, fixed numbers, or nested expressions. In the capstone it converts quantity and unit price into line revenue.

Expressions calculate a value inside a stage. They can read fields, compare values, perform arithmetic, or choose between two outcomes.

Course use: Exercise 12 and Hard Mode 13.

{ $multiply: ["$items.qty", "$items.unitPrice"] }