3.41: Counting 6-digit numbers from 9 digits

0606/23/O/N/25 — Question 5 · 6 marks

Six different digits are chosen from 1,2,3,4,5,6,7,8,91, 2, 3, 4, 5, 6, 7, 8, 9 and used to form a 6-digit number.
(a)
Find how many 6-digit numbers can be formed if there are no restrictions.
[1]
(b)
Find how many are greater than 700 000700\,000.
[2]
(c)
Find how many are greater than 750 000750\,000.
[3]