Four-digit numbers are formed from the digits 1 to 7 with no digit repeated. How many of them begin with an odd digit and end with an even digit?

Question

Accepted Answer

240. First digit: 1, 3, 5 or 7 (4 ways). Last digit: 2, 4 or 6 (3 ways). The middle two places take 2 of the remaining 5 digits in order: 5×4=20. Total 4×3×20=240.

Four-digit numbers are formed from the digits 1 to 7 with no digit repeated. How many of them begin with an odd digit and end with an even digit?

Step-by-Step Solution

Master this topic in 30 minutes a day.

More Permutations & Combinations practice