6, then ending 0 is not significant without a decimal
As of October 2011, around 5 trillion. See the link below.
10
None.
24 numbers.
There are 4 significant figures in this number.
There are 4 significant figures in this number.
There are 3 significant figures in this number.
There are 2 significant figures in this number.
There are 3 significant figures in this number.
The least number of significant figures in any number of the problem determines the number of significant figures in the answer.
There are four significant digits in the number 1.234
There are 4 significant figures in this number.