**OK, here's the deal...**

Choose a two-digit number (per Robin's instructions any two-digit number will work).

Speaking algebraically, let "X" represent the first digit and let "Y" to represent the second digit....and let "N" represent your 2-digit number.

so: **N** = **10X** + **Y**

Then Robin asks you to subtract the first digit ("X") and the second digit ("Y") from your original number. You'll use the resulting number (let's call it "G") as the "code" for a specific gift name you'll find on the chart.

so:

**G** *(Gift name)* = **N** *(2 digits)* - **X** *(1st digit)* - **Y ***(second digit)*

or algebraically: **G** = **N** - **X **- **Y**

Using substitution in the above equation:

**G** = (10X + Y) - X - Y = **9 X**

So, when you go the the chart, for whatever 2-digit number you've picked the code name will be a multiple of 9. And, then when you check out the chart, find your number (what's the gift?)...then add nine (what's the gift)...then add 9 (what's the gift?)

All the rest of the gifts on the chart are just there to distract you. Check it out...Nifty, eh????