MongoDB $multiply Operator

MongoDB provides different types of arithmetic expression operators that are used in the aggregation pipeline stages and $multiply operator is one of them. This operator is used to multiply one number to another number and returns the result. 


{ $multiply: [ <expression1>, <expression2>, ... <expressionN> ] }

Here, in this operator, the arguments passed in an array. The expression must be a valid expression until it resolves to a number. 


In the following examples, we are working with:

Database: GeeksforGeeks

Collection: employee

Document: three documents that contain the details of the employees in the form of field-value pairs.

Multiply using $multiply operator:

In this example, we are going to multiply the salary of the development department’s employees by 2.

db.employee.aggregate([{$match: {department: "Development"}},
... {$project: {name: 1, newSalary: {$multiply: ["$salary", 2]}}}])

Multiple using $multiply operator in the embedded document:

In this example, we are going to multiply the salary of the HR department’s employees by 3.

db.employee.aggregate([{$match: {department: "HR"}},
... {$project: {name: 1, newSalary: {$multiply: ["$details.salary", 3]}}}])

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