Dumb-o-meter question

This has been circulating awhile in the internet......

Me: Hey ask you a trick question.

Bits: Aha...(his default answer)

Me: Ben is 4 and his brother is half his age. When Ben is 100, how old is the brother?

Bits: 50.

Me: Det...wrong

Bits: Ben is 4...mumble mumble...100/2 ...mumble mumble... 50.

Me: Det...try again.

Bits: Ben is 4, brother is half his age means 2...so 100-2..... 96.

Me: Det....wrong, how can 100-2 is 96?

Bits: Wait....... 98.

Me: Ding ding... correct. Took you that long?

Bits: Not that long.....

Me: This question has been circulating in fb - used to test how smart your partner is...

Bits: (-___-")