Welcome to The Riddler. Every week, I offer up problems related to the things we hold dear around here: math, logic and probability. Two puzzles are presented each week: the Riddler Express for those ...

Calculating probabilities can be tricky, with subtle changes in context giving quite different results. I was reminded of this recently after setting BrainTwister #10 for New Scientist readers, which ...

The host invites you to pick a door, any door. Let’s say you pick door one. The host throws open one of the doors you did not select, revealing a goat. Then the host gives you the option of switching ...

Puzzles with counterintuitive solutions do more than challenge us. They expose how easily our fast, reflexive thinking can lead us astray. When the Monty Hall problem was first posed by Marilyn Vos ...