For this reason, you should always put a coin in your freezer

Travel Scenarios and the Coin Trick

The coin trick is pretty useful if you are going to be gone from home for extended periods of time. If you hadn’t used this trick, there would be no means of knowing whether the power had been cut when you were away. Upon your return, you could open a freezer full of food that appears all right, but has in fact, been subjected to unsafe temperature variations.

This trick regarding coins will give you the easy way out instead of guessing. You may sometimes find the coin deep down in the ice, revealing that something went wrong. Equipped with this know-how, you are now also enabled not to take in spoiled food, saving your body from food poisoning.