Question

The number of 4 digit numbers that can be formed from the digits 0, 1, 2, 3, 4, 5, 6, 7 so that each number contain digit 1 is.

• A. 1225
• B. 1252
• C. 1522
• D. 480

Answer 1

Answer: (D)

480

Answer 2

After fixing 1 at one position out of 4 places 3 places can be filled by $7P_{3}$ ways. But some numbers whose fourth digit is zero, so such type of ways = $6P_{2}$

∴ Total ways = $7P_{3} -^{6}P_{2} = 480$.