Question

Choose a three digit number that has no repeating numbers.
Write the digits in reverse order.
Calculate the difference between the two numbers.
Add the digits from the result.
Is your number 18?!

Answer 1

Answer:

With the element on the bottom, the warm water rises to the top, dragging down cooler water to replace it, ensuring all of the water heats. Additionally, you want the element to be immersed when heating a relatively small amount of water, so it doesn't heat air and get too hot.