Question

How many six digit numbers can be formed from digits 1 to 7 number?

Answer 1

there are six digits..

a b c d e f(say)

f=possible digits are 3 -(2,4,6)

e=possible 2 digits - (2,4,6)

and then rest...

d=possible 5 digits

c=possible 4 digits

b=possible 3 digits

a=possible 2 digits

the digits goes on decreasing since digits are not supposed 2 b repeated...

hence ans=>3*2*5*4*3*2=720...:)

Answer 2

$1 \times 6 = 6 \\ 7 \times 6 = 42 \\ 6(7 \: 8 \: 9 \: 10 \: 11 \: 12)42$