A recent trend in advertising is viral marketing. The goal is to convince viewers to share an amusing advertisement by e-mail or social networking. Imagine that the video is sent to 130 people on day 1. Each person agrees to send the video to 4 people the next day, and to request that each of those people send it to 4 people the day after they receive it. The number of viewers V (n) is an exponential function of the number n of days since the video was first shown.

I'm not sure what you are looking for but I'll answer this question based on what I think is needed.

Given:

Day 1: 130

Day 2: 130 x 4 = 520

Day 3: 520 x 4 = 2,080

The exponential equation of this problem is:

V (n) = 130 (4) ^n

Where n is the number of days since the video was first shown.

Let us assume that 10 days have past. Total view would be:

V (n) = 130 (4) ^n

V (10) = 130 (4) ^10

V (10) = 130 (1,048,576)

V (10) = 136,314,880

After 10 days, there are more than 136 Million views of the viral video.