999999-100000=899999numbers
* * * * *
Not quite. SInce 100000 is also a 6-digit number, the correct answer is 999999 - 100000 + 1 = 900000
It has 6 digits, all numbers.
6 if all digits are different, 27 otherwise.
900000
120 There are 6 digits in total. The numbers with 3 digits, with all digits distinct from each other, are the permutations of the 6 digits taken 3 at a time, and therefore there are 6*5*4 = 120 of them.
If the digits may not be repeated, there are 6x5x4x3x2x1 = 720 numbers, If digits can be repeated, the answer is 6x6x6x6x6x6 = 46,656 numbers If zero is ong the available digits but is excluded from the first place. 5x6x6x6x6x6=38,880 numbers
763920
6
There are 60480 numbers.
There are 6 such numbers.
Because all non-zero numbers are significant and any zeros in-between significant digits are significant, there are 6 significant digits in 10.0039.
6*5*4*3*2*1=720 possible numbers
10x10x9 = 900 ans.