I am a number between $15$ and $20$. If you divide me by $3$ and $4$, the remainders will be $2$ and $1$, respectively. Who am I?

How many single-digit natural numbers have exactly three factors?

I am an odd composite number; the smallest one that has two different primes in its tree. Who am I?

What is the HCF of two co-prime numbers?

Sarah makes chocolates and sells them during Christmas. This year she made $162$ dark, $216$ fruit and nut and $306$ strawberry chocolates. She wanted to pack them in such a way that each type of chocolate will be in a separate packet. But she also wanted each packet to contain the same number of chocolates. What is the maximum number that can be put in one packet if all the chocolates have to be packed?

Write the smallest $6‐$digit number and its predecessor.

Find the product of place value and face value of $7$ in $676130$.