What is the fastest way to double your money?

I know a nine-letter word having only one vowel.
Do you ?

Find the missing letter in the last circle logically in the given below picture.

What does the below rebus riddle means?

Can you find out the smallest number that can be conveyed as the sum of three squares in three unique ways?

It comprises roots which nobody sees,
Much taller than those trees,
Up and up it goes,
Still it never grows?

Find a 9-digit number, which you will gradually round off starting with units, then tenth, hundred etc., until you get to the last numeral, which you do not round off. The rounding alternates (up, down, up ...). After rounding off 8 times, the final number is 500000000. The original number is commensurable by 6 and 7, all the numbers from 1 to 9 are used, and after rounding four times the sum of the not-rounded numerals equals 24.

Andrew’s doctor gives him three pills and tells him to take one every half hour. How much time will have passed by the time Andrew’s taken all three pills?

A man stands on one side of a river, his dog on the other. The man calls his dog, who immediately crosses the river without getting wet and without using a bridge or a boat. How did the dog do it?

How can you take 2 from 5 and leave 4?