Question

if 0,1,2,3,4,5 and 6 are the numbers then how many ways to form three digits number greater then 330
?

Answer 1

Assumption: digits can be used at most one time.
There are 7 digits that could be used in the 3-digit number.
Because the number must be larger than 330,
there are 4 choices for the first digit: 3, 4, 5, 6.
Once one of those is taken, there are three left in that set.
One of them must be the second digit to keep the number above 330.
So, there are 3 choices for the second digit.
For the third digit, any of the original 7 digits that have not already been used can be selected.
Two have been used. That leaves 5 choices for the third digit.
Number of possible three-digit numbers with given constraint: 4 * 3 * 5 = 60