We were at Dawood Engineering College which was our center for our Third Year exams. It was 1969 and it was the day for the Fluid Mechanics II exam.
About 15 minutes before the center opened up, Ziauddin Qureshi (our classmate) approached me while we were waiting outside. He asked if I had any insights as to what may be asked. I told him that I was expecting a question about the drag/resistance to a thin plate being moved through a fluid. I also reviewed the answer and the formulas involved.
When we sat down and the question paper was distributed, the thin plate problem I had anticipated was there. I tackled the question first, and as I glanced in Ziauddin's direction, he looked up, smiled and gave me a thumbs-up. After the exam, we were all congregating outside comparing answers when Ziauddin approached and asked how I knew about problem being included in the exam. He was dumbfounded by my explanation.
What had happened was that on the previous day, our neighbor Abdul Rashid Khan's children were visiting our house. I was studying in a corner. I called the 7-year old girl over and asked her to open the Fluid Mechanics textbook (by Franzini and Dougherty). She randomly opened the book and it flipped to the page where the thin plate drag was explained and illustrated. I committed the solution to memory.
It was not a technical or scientific approach to preparing for an exam but in this case the random selection worked. The little girl is now an adult, lives in Korangi and is the mother of 4 children. Whenever I think of her help in 1969, I whisper a prayer for her and her family.