Determine the value of the number ABCD

An elderly woman went into the doctor's office. When the doctor asked why she was there, she replied, "I'd like to have some birth-control pills."

Taken aback, the doctor thought for a minute and then said, "Excuse me, Mrs. Smith, but you're 72 years old. What possible use could you have for birth control pills?"

The woman responded, "They help me sleep better."

The doctor thought some more and continued, "How in the world do birth control pills help you to sleep?"

The woman said, "Simple. I put them in my granddaughter's orange juice every morning and I sleep better at night."