Question

how many 4 digits number can be formed by using 1 2 3 4 5 6 without repeating how many of this solace

Answer 1

to form a 4 digit no. we have to complete ones ,tens,hundred and thousand

now we have 6 no. (1,2,3,4,5,6)

at ones place we can use any one of 6 no.
at tens place _ 5 no.
at hundredth place we can use any of remaining 4 no. and at thousand place we can use any 3 no.

so the 4 digit no. formed = 6×5×4×3 =360