12 M&M’s were originally created so that soldiers could carry chocolate without melting in warm weathers during World War II.

Forrest Mars, Sr., the son of Mars Company founder Frank C. Mars, used the idea for creating M&M’s when he saw the soldiers eating British made Smarties (chocolate pellets with a colored shell which prevented the candies from melting) during the Spanish Civil War in the 1930s. Mars received a patent for his own process of creating such candy and started production under the company name M&M Limited. During the Second World War the demand for the candies increased and were sold exclusively to the military at that time.(source)

13 Refrigerator doors are magnetic because kids were getting stuck inside of them. Prior to the Refrigerator Safety Act of 1956, the doors could only be opened from the outside by pulling the handle, resulting in the deaths of many kids who found abandoned refrigerators and got trapped inside while playing hide-and-seek.

During the 1950s, the refrigerators had latches on the outside to secure the door and so that it would be airtight. As children started getting trapped in them, many laws were passed, one of them calling it a felony if the refrigerators were kept in areas where the children could access them. Troops of people would sometimes search for abandoned refrigerators to detach the doors or break the latches. When the children were still dying inside refrigerators, a law was passed that required changing the way the doors stayed shut and led to the adoption of the magnetic mechanism that is used today.(source)

14 People used to use bread to erase pencil marks. In 1770, Edward Nairne accidentally picked up a piece of rubber instead of breadcrumbs, discovered its erasing properties and began selling rubber erasers.

In the past, crustless bread was used to erase pencil marks until Edward Nairne made his discovery which he presented at an inventions competition. Until then, rubber was called “caoutchouc” meaning “gum elastic” by the Native Americans. When Nairne started manufacturing his rubber erasers, he sold them for a high price of three shillings per half an inch cube. However, rubber was perishable, and in 1839, Charles Goodyear discovered vulcanization process which cured rubber making it more durable.(source)

15 WiFi was developed by using technology from a failed experiment attempting to detect mini black holes.

An Australian radio-astronomer Dr John O’Sullivan along with his colleagues developed a key patent used in WiFi as a byproduct of a research project they were working on. They were trying to detect exploding mini black holes the size of an atomic particle, which, however, failed. But in 1992 and 1996, the patents were obtained for a method that was later be used in WiFi to “unsmear” the signal.(source)

16 ATM PINs were originally intended to have six digits, but have four because the inventor’s wife said she could only remember that many.

When John Shepherd-Barron felt that he ought to be able to get his own money anywhere in the world or in UK at least, he “hit upon an idea of a chocolate bar dispenser, but replacing chocolate with cash”. The banking and financial services company, Barclays, immediately liked the idea and signed up a contract with him. Since back then, plastic was not yet invented, Shepherd-Barron used cheques that had carbon-14 in them which the machine detected and matched against a pin number. For the pin number, he felt that he should use a six digit number because he could remember his six-figure army number. But his wife, Caroline, said that she could only remember four numbers, and that was how we now have four digit pin numbers.(source)