When was the last time you used cash?
For lots of us, it's a bit of an anachronism. When you can tap your card, Stripe a credit card or use your smartphone to make a payment, hunting out the right number of coins and notes can seem pointlessly difficult.
But while everyone keeps predicting the death of cash, the amount we're using keeps growing.
There's about $6.5 billion of notes in circulation at the moment, which is getting near twice what it was ten years ago.
Theories for this increase vary but include things like people losing money or stashing it around their houses and forgetting about it, people using it for illegal purchases they'd rather no one knew about and the black market more generally.