How many numbers up to $100$ are divisible by $7$?

The sum of nine consecutive odd numbers of Set $A$ is $621$. What is the sum of a different set of six consecutive even numbers whose lowest number is $15$ more than the lowest number of Set $A$?

The unit digit in the sum $(124)^{372} + (124)^{373}$ is

$250 \%$ of $? \div 250 - 444 = 200$

What is the least number that must be added to $4042$ to make it a perfect square?

$0.01024 \times (0.4)^{9} = (0.4)^{?} \times (0.0256)^{3}$