Question

How many numbers can be formed taking 4 digits from digits 1, 2, 3, 4, 5, 6 whereas digit 4 and 5 are compulsory?

Answer 1

Total number of digits = 6

We Have to take 4 digits but digit 4 and 5 are compulsory.

Thus, we have to choose only 2 digits out of 6 – 2 = 4 digits.

Now, the numbers formed by using 4 digits is ⁴P₄.

Hence required number