Maybe you have already heard something about Electroneum, but for those who don't know what that is and what to do with i'll explain it. Electroneum (ETN) is a cryptocurrency that can be mined with a smartphone, requiring almost no technical knowledge or prior experience. This sets it apart from other cryptocurrencies (like Bitcoin) which require expensive hardware and technical know-how to mine.
Electroneum’s unique mobile mining experience allows anyone with a smartphone to earn ETN coins by letting the miner app run in the background. It doesn't drains more battery that a normal app and your phone won't get hot as if you would start mining other cryptos like Monero or Bitcoin.
You can collect all your old smartphones and let them mine ETN for you. It doesn't matter how powerful your device is. My Samsung Galaxy S7 had the same hashrate as my S3 because as said it doesnt really mine but you earn money though. I managed to earn 20 - 25€ just by letting my old mobiles mining. That is good earned passive money. It gets much more profitable in countries where the currency costs are very low.
Just download the Electroneum App from the Play Store or App Store and use the code below to get 5% of my mining earnings!
395996
Here some screenshots of that earned money that I got since yesterday: