physics
posted by mack .
the centers of two 5000 kg blocks are separated by 1.13 m.
What is the gravitational force between the two blocks?
What must be the distance between the centers of the blocks if the gravitational force decreases 25 times?

(1) F = G*M1*m2/R^2 = G *(5000)^2/(1.13)^2
Look up the value of G and compute.
(2) Five times more than 1.13 m, because of the inverse square dependence upon distance. . 
I have the formula down ok. My problem is with the exponents. G = 6.67 x 10^11. M1 and m2 = 25,000,000. I wrote down m1 and m2 as 2.5 x 10^7. I multiplied 6.67 by 2.5 and come out with 16.67. I do not know why but I know I need to move the decimal point over and come up with 1.6675 x 10^3. My denomenator comes up to 1.2769. Does this sound right?