What has three feet but can not walk?

A grandmother, an aunt, two mothers, two sisters, three daughters, a niece, and a granddaughter all went out to eat together. Everyone ate one ten dollar plate. If the grandmother and one of the mothers paid the entire bill, how much money did the grandmother have to pay?

You have 20 pairs of black socks and 20 pairs of white socks all mixed up in your sock drawer. There are no lights on so you can't see the color of your socks. What is the smallest number of socks you can pull out of your drawer to make sure you get 1 matched pair of either black or white socks.

What is 4 x 5 x the half of 2 x 50000 x the half of 8 x 65 x 9786 x 45320 x 9500 x the half of 30?

2,8,20,44,92,188,380,764

Can you tell the logic behind this number series?

Use only 8's to make 1000. You Can only use addition operation.

What is the answer?