Math Problem Tips helps?

Question

How can you simplify (2.5x10^-7) (4.8x10^11) over (6.4x10^3)^1/2

without using a calculator, I know how to do the numerator it gives me 120 000, but the denominator its hard any tips? I can't squaroot 6.4...

by the way the answer has to be simplified with the power of ten

Answer 1

6.4 * 10^3 = 64 * 10^2

the 1/2 power is the same as a square root

sqrt(64) = 8

sqrt(10^2) = 10

sqrt(64 * 10^2) = 80

the denominator simplifies to 80...

the numerator simplifies to 12 * 10^4 = 120,000

120,000 / 80 = 12000/8 = 1500 = 1.5 * 10^3

Answer 2

you don't know what times what is 64?  it's 8