Japan teacher reprimanded for murderous maths quiz

A Japanese primary school teacher has been reprimanded for giving his pupils a maths problem in which he asked how long it would take to kill 18 children at a rate of three murders a day.

This is up there in the league of getting students to raise a pig with the objective of eating it in due course.

LOVELY!

Any prizes for the correct answer?!!
*waves both hands in the air* Choose me! Choose me!!