If 25% of a number is 6, what is the number which is 50% more than the initial number?

Let the initial number be x.

$\therefore x \times \frac{25}{100}=6 \Rightarrow \frac{x}{4}=6$

$\Rightarrow x=4 \times 6=24$

$\therefore$ Required number $=\frac{24 \times 150}{100}=36$