Question

Help many fore digits numbers are there
beetween 999 & 10, 000​

Answer 1

Answer:

There are 6 digits (0, 2, 3, 6, 7, 8). Ten thousand place can be filled with 2, 3, 6, 7, 8. Thus 5 digits can be used in constructing the unit place.

Now, from the rest 5 no. we can use only 3 nos. at a time. Then the second digit can be selected in 3! i.e. 6 ways. And the rest no. in ways. Thus the total nos. lying between 999 to 10,000 are:

.