The full moon rose over the horizon and lit up the grasslands, which had a light dusting from the winter snow that had fallen the day before. Moonlight streamed in through the front window and lit up the room where Small Number, his sister Perfect Number, and their cousins were sitting around the fireplace talking about the new pair of kit foxes that had been settled that day near the rocks beside the creek way out by the furthest edge of their grandparents' ranch. Grandpa sat quietly in his chair in the corner, not showing his own excitement at the return of kit foxes to the area, where they had not been seen since his father was a young man. Grandma came in and closed the curtains, causing the children to look up from their game as the room darkened. The children knew it would soon be time for them to go to bed, and so they excitedly started pestering their grandmother with questions about the kit foxes to distract her.

"Pleeeeease, Grandma! Tell us about the kit foxes! Please!" they all pleaded in unison. "When will they have babies?"

Grandpa had a sparkle in his eye as he took up their cause and played along: "Yes, Grandma, tell us about the kit foxes."

Grandma gave Grandpa a stern look that would have frozen water in mid-summer before it dissolved into a soft smile as she sat in her chair and looked down at the children who had gathered at her feet. She didn't start speaking right away, but waited patiently until the fidgeting children settled down and stopped poking and teasing each other.

"Young kit foxes always obey their parents. Always." Small Number blushed when he realized his grandmother was looking directly at him. He tried hard to believe that a slight turn of a smile appeared on her face before she released him from her gaze and went back to her story.

"The kit fox likes to come out late into the night, just before the first light of the dawn. You will not likely see her during the day. When the wind blows, she will hide from it in her den and only come out when it stops. When she is going to have pups, she gets her den ready for them by covering the floor with prairie grass. Once the pups are born, she will stay in the den with them and go out only to hunt regularly so she can continue to nurse her pups."

Small Number interrupted her: "Does she hunt every day?"

"No, not everyday, " she replied. "When she goes hunting, they will stay behind in the den and wait for her. They know not to leave the den when she is gone. The pups won't come out of the den at all until they are old enough."

"But what about the boy kit fox, Grandma? Doesn't he love the girl kit fox and want to stay with her?" interrupted Perfect Number. Small Number rolled his eyes. His sister always seemed to talk about boys lately.

Before Grandma could answer, Grandpa spoke softly: "The boy kit fox loves the girl kit fox and wants to be with her." He looked at Grandma as he said this, and she nodded her head, her eyes smiling at him.

"Yes, Perfect Number, the boy kit fox wants to stay with his mate for all time, and she wants him to be near her. They will sit under the moonlight tonight and feel the happiness of returning home to this territory. They belong here in the grasslands. The buffalo knows this and will feel contentment that the kit foxes are making their home near her. She will visit them tonight to welcome them home."

"But when will they have babies, Grandma?" Perfect Number asked plaintively.

"Soon. The den where she lives is not big enough to have the boy kit fox in it, too, when she has their pups, so he will live nearby and want to see her as often as he can. But she will only come out to hunt, and so he must be patient." She looked over at Grandpa, who smiled and nodded his head.

"He will want to see her again under the full moon to share their remembrance of the joy of this day, the day they have returned home. He knows how many days he must wait and he makes a scratch in the wall of his den for each day that passes so that he can keep track of the time."

"When will that be, Grandma?" asked Perfect Number.

Grandma looked down and said nothing for a while. She was thinking for a long time. The children started fidgeting, but stopped when she looked up.

"They will get to see each other when she comes up to hunt under the light of the full moon twelve quarter moons from now," Grandma said with certainty.

Small Number cocked his head and looked puzzled: "How do you know that, Grandma?"

"I know how often kit fox will come up to hunt," said Grandma.

"How often is that, Grandma?" the children said in unison.

She did not say anything because she saw the children were trying to work out the answer.

"I know! I know!" shouted Perfect Number. She jumped up, ran to Grandma, and climbed onto her lap. She whispered something in Grandma's ear so only she could hear her.

Grandma smiled. "You are clever, Perfect Number!"

Question: If kit fox leaves her den at a regular intervals, how often does the kit fox leave her pups to come up to hunt?