Good profile in Fortune of the Acorns investing app

http://fortune.com/2017/02/14/acorns-app-investing-robo-advisor/

“A recent study of Acorn’s customers found that people were much more likely to agree to set aside $5 per day than $150 per month, even though they’d end up contributing the same amount either way. Indeed, if an 18-year-old started putting away just $5 per day, by the time they reached retirement age at 65, they’d “have almost $1 million set aside through Acorns,” Kerner says (assuming a compound annual return of 8%).”