By rounding each value to one significant figure, estimate the cost of 3.9kg of apples at 87p per kg

The number of branches on a tree demonstrates the fibonacci sequence. how many branches would there be on the next two levels of this tree? 13 | | | m branches

He mass of a single atom of carbon can be found by dividing the atomic mass (12.01 g) by 6.022 x 10^23. which is the mass of a single carbon atom, correctly written in scientific notation with the correct number of significant figures?

How many sides does a regular polygon have if each exterior angle measure is 45 degrees explain your answer, i really don't understand this.