Can you replace the question mark with the number to complete the series, provided the pair of numbers exhibits a similar relationship?

? : 4623 :: 9 : 647

Can you find the last number in the number sequence given below?

10 : 10 : 20 : 45 : 110 : 300 : ?

Can you find the missing number in the sequence given below?
11 15 19 12 16 ? 13 17 21 14 18 22

Can you replace the question mark with the number to complete the series, provided the pair of numbers exhibits a similar relationship?

? : 4623 :: 9 : 647

You need to pick any number from '1, 3, 5, 7, 9, 11, 13 and 15' to make below equation true.
( ) + ( ) + ( ) = 30

Can you solve it ?

Ramanujan found out that 1729 is a magical number.

What is so magical about it ?

If in a cricket one day match, there were no wide balls, no wides, no extras and no overthrows.

What is the maximum number of runs that a batsman can score in an ideal case scenario?

A claustrophobic person boards a train that is just about to enter a tunnel.

Which place will be the best for him to sit?

If
2-1=3
4-4=0
8-5=40
10-10=???

10×11×12=9
11×12×13=9
12×13×14=9
13×14×15=9
14×16×20=?