Digits after decimal point

The number $(\sqrt{a}+\sqrt{b})^{2n} +(\sqrt{a}-\sqrt{b})^{2n}$ is integer.

$\sqrt{7}-\sqrt{5} <1$

$(\sqrt{7}-\sqrt{5})^{1000} <{0.000001}$

So the first digits after the decimal point are 9999.