How many five-digit numbers (repetition is not allowed) can be formed by using digits 1-7, if two is always there in the number?

1200

No worries! We‘ve got your back. Try BYJU‘S free classes today!

1800

Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses

2400

No worries! We‘ve got your back. Try BYJU‘S free classes today!

5400

No worries! We‘ve got your back. Try BYJU‘S free classes today!

Open in App

Solution

The correct option is B 1800
As two is already included, four more digits are required to be selected out of 6 digits.
The number of ways of selecting the numbers = 6C4 = 6C2 = 15 ways
Also, five digits can be arranged amongst themselves in 5! = 120 ways.
Hence the total no. of possibilities $= 120 \times 15 = 1800$ ways.

Suggest Corrections

Similar questions

4 -

1

9

How many three digit odd numbers can be formed by using the digits 1,2,3,4,5,6 if the repetition of digit is not allowed:

1000

0, 3, 5, 7

4321

1, 2, 3, 4,

Join BYJU'S Learning Program