how many 6 digit telephone number can be constructed with the digit 0,1,2,3,4,5,6,7,8,9, if each number starts with 35 and no digit appears more than once

If the no. starts with 35 then out of six digits two digits are fixed so four digits places are left.

The four places can have any value from these eight nos. 0,1,2,4,6,7,8 and 9.

But since the repeatation of digits is not allowed so the total no of 6 digit telephone number which starts with 35 can be 8 x 7 x 6 x 5 = 1680.