Daily Digit is the story behind the numbers that make our world work. Today we’re looking into the rapid growth of artificial intelligence (AI). While it may seem like something out of a science fiction film, assistants that artificial intelligence — like Apple's Siri and Amazon's Alexa — are on track to outnumber humans by 2021. As the number of devices supporting digital assistants grows, so does the number of installations on devices. Over the next three years, the number of digital assistants is set to exceed 7.5 billion, and that figure will grow exponentially as the technology improves. However, we're far from a robot takeover. There's no reason to fear AI — at least not yet.