Question

How many 4 digit numbers can be formed by using 1,2 ,4, 5 ,6 ,7 cannot be repeated?

Answer 1

Answer:

15

Step-by-step explanation:

Forming 4 digits number using 1,2,4,5,6,7

at total there are 6 numbers

repeatation is not allowed

then it is combination

6C4=6!/(6-4)!4!=6!/(2!*4!)=5*6/2=15

therefore there are 15 four digits numbers can be formed