Who named the centre of the cell as nucleus?

Each side of a square is 10 meters long. A rectangle of the same perimeter as this has sides in the ratio 2:3. What is the area of the rectangle in square meters?

One year in the nineteenth century, the mathematician De Morgan remarked, 'my age now is the square root of this year'. When was De Morgan born?

2.5 bottles of the same size are filled with 1.5 litres of water. How many millilitres does each bottle contain?

What is the remainder on dividing the sum 2 + 2 squared + 2 cubed + ... + 2 to the power 10 by 10?