You need to multiply the two numbers. Or you can use long addition.
It is the circle which has its radius a 0units and it can also be called as a point circle.
A conservative vector field

has curl

. In this case,

so the vector field is not conservative.
6.875 average.
To calculate the average you add up all of the numbers and divide it by the number of numbers there are, in this case there are 4 numbers. So you add 3.25+6.5+7.25+10.5 and divide that by 4