Find the HCF of $15 \& 16$.

Find the least number, which is divisible by $8 \& 9$.

Let us find mentally:

$6$ multiples of $5$ which do not contain $\text{'}0\text{'}$.

Let us find mentally:

Let us find $3$ multiples of $7$ which are greater than $50$.

Find $2$ Two-digit numbers which are multiples of $4$.

Find three factors of $4$.