In a row of girls, Shilpa is $8^{th}$ from the left and Reena is $17^{th}$ from the right. If they interchange their positions, Shilpa becomes $14^{th}$ from the left. How many girls are there in the row?

How many days will there be from $26^{th}$ January,$1988$ to $15^{th}$ May,$1988$ (both days included)?

How many numbers from $1$ to $100$ are there,each of which is not only exactly divisible by $4$ but also has $4$ as a digit?

$(I)$ Kamal is available at home from $12$ noon to $4 \,p.m.$ on Tuesday,Thursday,and Sunday.
$(II)$ His younger brother Navin is available at home on Monday,Thursday,Friday,and Sunday between $10 \,a.m.$ to $2 \,p.m.$
$(III)$ The eldest brother Rajiv is available between $9 \,a.m.$ to $12$ noon on Monday,Wednesday,and Thursday and $2 \,p.m.$ to $4 \,p.m.$ on Friday,Saturday,and Sunday.
For how many days is only one brother available at a particular time in a week?

In the following series of numbers,find out how many times $1, 3$ and $7$ have appeared together,with $7$ being in the middle and $1$ and $3$ on either side of $7$?
$2, 9, 7, 3, 1, 7, 3, 7, 7, 1, 3, 3, 1, 7, 3, 8, 5, 7, 1, 3, 7, 7, 1, 7, 3, 9, 0, 6$

If $16 \times 85 = 8651$,what is $73 \times 42$?