Corrupt Servant Stealing The Gold

You have 10 bags of gold coins.You have appointed 1 servant to carry each bag. One of your servants who were responsible for transport of the money wanted to trick you. He took one of the bags and filed away one gram of gold from each coin. One coin normally weighs 10 grams.

Can you figure out in one scaling which bag contains lighter coins? Which servant should be fired? – using digital scales (shows the exact weight of an item)?

Trick to get down the culprit! 

Source

Master Plan for Gold Stealing Servant

Where story begins? 

We need to take coins from each of 10 bags to test.

Number all the servants & their respective bags from 1-10. Now take 1 coin from first bag, 2 coins from second bag, 3 coins from third bag & so on to 10 coins from tenth bag. Put all those on digital scale. In normal case, with no corruption it would weigh in the case as 55 x 10 = 550 gm. But coins from one of the bag weighs 1 gm less. So if it weighs 1 gm less then 1st coin that came from first bag is filed one & hence first servant is corrupt. If it weighs 548 gm then coins from second bag are reduced ones & hence second servant is corrupt.

Depending on how many gm less than 550 gm it weighs the bag with manipulated coins can be identified & respective servant can be fired.