How do blind people figure what kind of dollar they're being handling? After all, aren't $1 and a $20 bills all the same size? You may be surprised to know that every major currency issuer in the developed world has found a way to solve this problem—except the US. (1/5)

In the United Kingdom, like in many countries, bills vary in length, with higher bills naturally being longer. It's probably slightly too subtle for most people to notice, but it's immediately obvious to a blind person who knows what to look for. (2/5)

Many other currencies, like the Euro, combine length variation with intaglio printing—essentially, raised numbers that you can easily feel. Again, too subtle for most people, but a lifeline for the blind. (3/5)

Similarly, the Canadian incorporates tactile marks that signal the bill's value. Slightly more opaque than intaglio printing, but likely a familiar mechanism for folks used to reading brail. (4/5)

@mnolangray Of the solutions you describe, I like this the best. It's useful for people other than the blind, and it doesn't make some forms of storage more awkward by varying bill dimensions.

@mnolangray There are also plastic cards around that can help measuring and identifying banknotes.

@mnolangray Wait, really? Oh wow, I live in Latvia, we have euros here, and I never saw that! I do think there are also size differences, but dang, this is actually really cool.

@mnolangray Our banknotes in the UK are now polymer, not paper, so they're now tough enough to have some braille-style raised bumps to let blind people know which denomination note they have AND which side is which and which way round it is (so you can put them in vending machines correctly)