[{"_id":ObjectId("5e2f408b1548343a74dce68a"),"employee_first_name":"Gwenaëlle","employee_last_name":"Shawley","department":"Product Management","salary":"$205223.43","years_in_job":17,"dob":"4/12/1980","childrenId":[ObjectId("5e2da031c71c0b0f54e35236"),ObjectId("5e2da031c71c0b0f54e35234"),ObjectId("5e2da031c71c0b0f54e35235")],"updatedAt":ISODate("2020-02-06T16:47:29.208Z")},{"_id":ObjectId("5e2f408b1548343a74dce17b"),"employee_first_name":"Gwenaëlle1","employee_last_name":"Shawley1","department":"Product Management","salary":"$205223.43","years_in_job":17,"dob":"4/12/1989","childrenId":[ObjectId("5e2da031c71c0b0f54e35236"),ObjectId("5e2da031c71c0b0f54e35235")],"updatedAt":ISODate("2020-02-06T16:47:29.208Z")}]

db.collection.aggregate([{$match:{department:"Product Management"}},{$group:{"_id":"$years_in_job",total:{$sum:{$toDouble:{$substr:["$salary",1,-1]}}}}}])