Haven’t you ever wanted to know how to make sure a Canadian SIN number is valid? This could come in handy when doing surprise credit checks on your friends…

1. Write down your sin. For example: **044-096-857**

2. Re-write your sin, but this time, double the **2nd**, **4th**, **6th**, and **8th** digits. Write the number exactly as it appears when doubled, even if it is now a 2-digit number. For example: 0**4**4-**0**9**6-**8**5**7 becomes 0**8**4-**0**9**12-**8**10**7.

3. Add up each **individual number** in the new sequence. For example: **0+8+4+0+9+1+2+8+1+0+7 = 40**.

4. If the sum is a **multiple of 10**, then the SIN number is valid. For those mathematically-challenged readers, if the sum ends with a “0”, then the SIN is valid.

Now that you know, go impress your friends.