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How to calculate the number of gifts in 12 days of Christmas?

Published in Christmas Song Mathematics 3 mins read

The exact total number of gifts received throughout the "Twelve Days of Christmas" song is 364.

This classic carol accumulates gifts over 12 days, with each new gift type added to all subsequent days. Understanding how these gifts add up reveals the fascinating mathematics behind the song.

Understanding the Gift Accumulation

In "The Twelve Days of Christmas," the gift-giving is cumulative. This means that on each subsequent day, the previous days' gifts are given again, in addition to the new gift(s) for that specific day. For example:

  • On the first day, you receive 1 Partridge in a Pear Tree.
  • On the second day, you receive 2 Turtle Doves and another Partridge in a Pear Tree.
  • On the third day, you receive 3 French Hens, 2 Turtle Doves, and 1 Partridge in a Pear Tree, and so on.

To calculate the total number of items received, we need to count how many times each specific type of gift is given over the entire 12-day period.

  • A Partridge in a Pear Tree is given on Day 1, Day 2, ..., Day 12, for a total of 12 times.
  • The 2 Turtle Doves are given on Day 2, Day 3, ..., Day 12, for a total of 11 times (2 doves × 11 days = 22 doves).
  • The 3 French Hens are given on Day 3, Day 4, ..., Day 12, for a total of 10 times (3 hens × 10 days = 30 hens).
  • This pattern continues for all 12 types of gifts.

Calculating the Total Gifts

To determine the grand total, we sum the cumulative count for each gift type. An efficient way to calculate this total is to observe a unique pairing pattern in the number of gifts received:

Gift Type Given on Days Number of Times Given Total Items of This Type
1st: A Partridge in a Pear Tree 1-12 12 1 × 12 = 12
2nd: 2 Turtle Doves 2-12 11 2 × 11 = 22
3rd: 3 French Hens 3-12 10 3 × 10 = 30
4th: 4 Calling Birds 4-12 9 4 × 9 = 36
5th: 5 Golden Rings 5-12 8 5 × 8 = 40
6th: 6 Geese A-Laying 6-12 7 6 × 7 = 42
7th: 7 Swans A-Swimming 7-12 6 7 × 6 = 42
8th: 8 Maids A-Milking 8-12 5 8 × 5 = 40
9th: 9 Ladies Dancing 9-12 4 9 × 4 = 36
10th: 10 Lords A-Leaping 10-12 3 10 × 3 = 30
11th: 11 Pipers Piping 11-12 2 11 × 2 = 22
12th: 12 Drummers Drumming 12 1 12 × 1 = 12

By summing the "Total Items of This Type" column:
12 + 22 + 30 + 36 + 40 + 42 + 42 + 40 + 36 + 30 + 22 + 12 = 364

An Elegant Calculation Method

An easy way to calculate the sum is to notice that certain gift types result in the same total number of items:

  • Partridges (12) and Drummers (12)
  • Doves (22) and Pipers (22)
  • French Hens (30) and Lords (30)
  • Calling Birds (36) and Ladies (36)
  • Golden Rings (40) and Maids (40)
  • Geese A-Laying (42) and Swans A-Swimming (42)

Therefore, you can sum the totals for the first six unique gift types and then double the result:
(12 + 22 + 30 + 36 + 40 + 42) × 2 = 182 × 2 = 364

This method efficiently confirms that the total number of gifts received over the twelve days is 364.