Variation of gravitational attraction between Sun and Earth

[Matthew 289]

Homework Statement

Distance Earth-Sun at perihelion = 1.471×10⁸ km
Distance Earth-Sun at aphelion = 1.521×10⁸ km
Sun mass = 2.0×10³⁰ kg
Earth mass = 5.972×10²⁴ kg
G = 6.67×10^-11 m³/kg⋅s
What is the change in Newton of the attraction force between the Sun and the Earth from the perihelion to the aphelion ?

Homework Equations

F= G × M_sun×M_Earth/distance²

The Attempt at a Solution

F_perihelion= (6.67×10^-11 m³/kg⋅s) × (2.0×10³⁰ kg)×(5.972×10²⁴ kg)/(1.471×10⁸ km) = 3.68×10²⁸ N

F_aphelion= (6.67×10^-11 m³/kg⋅s) × (2.0×10³⁰ kg)×(5.972×10²⁴ kg)/(1.521×10⁸ km) = 3.44×10²⁸ N

ΔF= |F_perihelion| - |F_aphelion| = 3.68×10²⁸ N - 3.44×10²⁸ N = 2.4×10²⁷ N

My problem:
The result does not correspond to that given by the textbook (2.37×10²¹ N).
I cannot see the fault in my resolution and other methods I've tried give wrong answers as well.
Can anyone see my mistake/s ? Is it logical or arithmetical ?

 

[PeroK]

My problem:
The result does not correspond to that given by the textbook (2.37×10²¹ N).
I cannot see the fault in my resolution and other methods I've tried give wrong answers as well.

What if you were given the distances in miles, instead of km?

 

[Saurabh]

First of all, you haven't squared the distance in the solution.
I don't have a clue of the calculations.
And secondly, convert kilometers into meters and then square.
that means 10^(8) changes to 10^(11) first since 1 km = 10^3 metres
Then, squaring becomes 10^(22)
rest of the method is alright,
i have solved it. and got the correct answer.
peace!

 

[Matthew 289]

First of all, you haven't squared the distance in the solution.
I don't have a clue of the calculations.
And secondly, convert kilometers into meters and then square.
that means 10^(8) changes to 10^(11) first since 1 km = 10^3 metres
Then, squaring becomes 10^(22)
rest of the method is alright,
i have solved it. and got the correct answer.
peace!

Thank you very much ! I've done what you've suggested and the answer was right !
Have a nice day.