Let $S_n$ denote the sum of the cubes of the first $n$ natural numbers and $s_n$ denote the sum of the first $n$ natural numbers. Then $\sum _{r=1}^n\frac{S_r}{s_r}$ equals

Which of the following should come in the place of '?' ?

$\mathrm{AB}3, \mathrm{DE}6, \mathrm{HI}10, \mathrm{MN}15, ?$

What will come in the place of question mark in the given number series:

$142, 70, 34, 16, ?, 2.5$.

What will come in place of the question mark (?) in the following number series:

$48, 23, ?, 4.25, 1.125$

What should come in place of the question mark for the following question:

$1, 244, 163, 190, 181, ?$

What will come in place of question mark (?) in the following number series:

$2, 15, 41, 80, 132, ?$

What will come in the place of the question mark in the given number series:

$0.75, ?, 6, 36, 288, 2880$.

What should come in place of the question mark for the following question:

$256, ?, 190, 167, 148, 131$

What should come in place of the question mark in the following question:

$36, 18, 6, 3, 1, ?$

What will come in place of the question mark (?) in the following number series?

$?, 15, 75, 525, 4725, 51975$

The following series is based on the English alphabets and numbers, which of the following will come in place of the question mark in the given series?

XW2    TS6    PO10    LK14    ?

What will come in the place of question mark for the following number series:

$21, 37, 40.2, 88.2, 94.6, ?$.

What should come in place of the question mark in the following question:

$18, 29, 42, 53, ?, 77$

What should come in place of the question mark in the following question:

$18, 8, 6, 9, 32, ?$