uint aScaled = a * (10**10);
uint divScaled = a / b;            // b is not scaled!

uint n = divScaled / (10**10);
uint dec = divScaled mod (10**10)

a = 3; b = 2;
aScaled   = 3 * 10000000000;           // = 30000000000
divScaled = 30000000000 / 2;           // = 15000000000
n         = 15000000000 / 10000000000; // = 1
dec       = 15000000000 mod 1000000000;// = 5000000000