A maths puzzle aimed at Year 2 students has adults across the internet stumped.
Shared to Twitter by UK mum Louise Bloxham, the question reads: "There were some people on a train. 19 people get off the train at the first stop. 17 people get on the train. Now there are 63 people on the train. How many people were on the train to begin with?"
Not alone in her bewilderment, Bloxham's followers were also confused as to what the correct answer could be.
One method, offered by Robyn Duckworth, was to subtract 19 from 65 and add 17 to get 63.