var connectionString = "mongodb://localhost:27017";
var setting = MongoClientSettings.FromConnectionString(connectionString);
setting.LinqProvider = LinqProvider.V3;
var mongoClient = new MongoClient(setting);

var db = mongoClient.GetDatabase("test");
var coll = db.GetCollection<CallRecord>("calls");

var result = coll.AsQueryable()
    .Select(p => new {name= p.PhoneNumber,DurationInMinute = Math.Ceiling((float)p.Duration / 60) });

var array = await result.ToListAsync();

foreach (var record in array)
{
    Console.WriteLine($"phone:{record.name},Duration:{record.DurationInMinute}");
}

public record CallRecord(string PhoneNumber,int Duration); 

Unhandled exception. MongoDB.Driver.Linq.ExpressionNotSupportedException: Expression not supported: Convert(p.Duration, Single) because conversion to System.Single is not supported.
   at MongoDB.Driver.Linq.Linq3Implementation.Translators.ExpressionToAggregationExpressionTranslators.ConvertExpressionToAggregationExpressionTranslator.Translate(TranslationContext context, UnaryExpression expression)