Because 7 kills people twice weekly.
6 was afraid that he was next, with all the rest of the single digit numbers gone
The local police were doing the best they could
But 7 was too crafty
Even the double digit upper government officials couldn't get him. He was a madman on the loose, and nobody was safe
Everyone knew the rare and treasured non-real and negative integers were going to be next, once 6 was gone
But 6 wasn't going down without a fight
Every day 6's every step was carefully placed.
Everywhere 6 went he went with the heightened awareness of the expectancy of an attack.
Most of the town was barren and empty, except for some smaller decimals playing in the street, so 6 was a wide open target
As the days went on, unfortunately the pressure got to 6 and he flipped.
At 10:42 am he left his house, fell to his knees in front of 7, who he knew was hiding nearby
And screamed "I'M DONE WITH THE PRESSURE. MAKE IT END, PLEASE. YOU'VE WON. TAKE MY LIFE, THERE'S NOTHING LEFT FOR ME HERE"
And without a word, 7 slid out of the shadows and in a fraction of a second 6 had become just a circle and a slightly curved segment.
He lay in pieces on his own front walk, and as 7 vanished once more into darkness, Numeriland fell to it's own knees in a last surrender to the world's mastermind criminal. The number 7.
This was a little story I came up with on the fly, based on the very first statement. I just kept expanding on it, until it sounded like a suspense thriller movie. Tell me what you think!