和老爸聊天，他出了一個題，，，你的答案？

My dad has watched a variety TV program recently. He recalls that I even had

known the answer of one question when I was in my elementary school. 

The following is the question and what is your answer？

In a big lake， due to the heavy rain， the amount of water is doubled every day. On day thirtieth, the lake is full. On which day is the lake with half of the water？

所有跟帖： 

• binary math is what we programmers do best: 29th -7grizzly- ♀ (0 bytes) () 04/23/2023 postreply 12:00:36

• 學習了binary math：） -妖妖靈- ♀ (0 bytes) () 04/23/2023 postreply 16:06:14

• brain teaser -移花接木- ♂ (0 bytes) () 04/23/2023 postreply 19:40:13

• 電視上有人說一星期什麽的，智商太低了：） -妖妖靈- ♀ (0 bytes) () 04/23/2023 postreply 20:15:25