How many mince pies?

A Christmas maths and physics challenge! Danger - may contain spreadsheets

I'm currently asking my colleagues a series of questions to win the chance to open the door on my DisneyPixar Advent Calendar.

Friday's challenge was to work out how many mince pies Santa would need to feed his reindeer to fuel for a practice run of the the delivery of presents around the world after abandoning checking the list.

Assumptions and information:

• The mince pie is a Sainsbury's Taste the Difference Brandy Rich Mince Pie at 242 kcal a pop
• Santa has decided making a list and checking it twice is inefficient so gives all 2 billion children a present
• On average, each house is 250m apart
• There are 2.4 children per house
• Santa chooses the most efficient route with no doubling back
• Each children receives a present weighing 1kg
• Santa and each reindeer weights 150kg
• Each reindeer can pull 150kg of additional weight
• Force to move 1 kg is 10 newtons
• Santa's sleigh flies magically and no energy for maintaining altitude is needed
• As it's a dry run, the sleight remains fully loaded
• Ignore the weight of the mince pie
• Ignore quantum theory, air resistence, acceleration etc

And for a further bit of trivia, this is 309 times more calories than the entire world eats every year! I think if presents were delivered you would essentially halve the energy needed for the presents, but you'd need the same number of reindeer for the peak load, so calories/pies would be reduced by 25%.