We (people) take more time to multiply, add, divide and subtract two large numbers than two small numbers.
Does a computer take more time to multiply 5 * 2 than say 51234 * 987654 or is the operation done in same amount of time?
What about two numbers that are greater than word size of the processor (e.g. two 128 bit number)?
I saw the article https://en.wikipedia.org/wiki/Multiplication_algorithm