Reindeer Numbers

We delivered Christmas maths problems for earlier grades in a previous blog post recently, and now here's one for upper primary. 

This one will really get the studnets things:

One of Santa's best kept secrets is that there is a special link between a reindeer and its number. Indeed, a reindeer number has the property that it is equal to the product of two of the numbers (known as antlers) that can be made with its digits. For example, 1827 is a reindeer number with antlers equal to 21 and 87, because 1827 = 21 × 87. Sometimes one of the antlers gets broken (i.e. is 1 out) like
3456 which is the number of a reindeer with a broken antler:

3456 = 64 × 54 and just one digit is 1 out.

On the night before Xmas, the reindeers with these reindeer numbers reported for duty:

1827 2187 1435 3456
1932 2496 6880 8190
1530 3864 1395 7189

"It's wonderful to see you all," Santa said... "but I can only use reindeers whose antlers are not broken. It's a long journey, and you will need all the antler power that you can get if we are to deliver all the presents."

Ask students to help Santa sort out which of the reindeers he can use to pull his sleigh.

"Now, where is my friend Rudolf?" Santa said. "I can't go without him!" Rudolf has the smallest reindeer number and a complete set of antlers, but he hasn't reported for duty yet. What reindeer number should Santa go looking for if he is to find Rudolf?

There will be loads more Christmas themed problems to come that we'll share via our blog in the lead up to Christmas so stay tuned.