HP-15c: Why so popular?

[Jlouis]

For those who says it was not so popular, I must remember you that the HP 15C was reissued two times, since its ended production in 1989, the first time with a petition for HP with thousands signatures. If it's not popularity, you name it.

Tell me another calculator that did this.

As for the reason for its success, among others already mentioned here, the landscape form factor is very important. By the way, the popularity of the 12C is not coincidence too.

Cheers

JL