# Advent calendar 2019

## 9 December

Arrange the digits 1-9 in a 3×3 square so that:
all the digits in the first row are odd;
all the digits in the second row are even;
all the digits in the third row are multiples of 3;
all the digits in the second column are (strictly) greater than 6;
all the digits in the third column are non-prime.
The number in the first column is today's number.

all odd | |||

all even | |||

all multiples of 3 | |||

today's number | all >6 | all non-prime |