8
20Each of the numbers 8, 18, ... 98 has an 8 in the units digit. That's 10 8's.Each of the numbers 80, 81, ... 89 has an 8 in the tens digit. That's 10 more 8's.(You could do this yourself just by writing down all the numbers.)
57
-5
720 (10*9*8)
8
That makes:* 8 options for the first digit * 8 options for second digit * 10 options for the third digit * ... etc. Just multiply all the numbers together.
20Each of the numbers 8, 18, ... 98 has an 8 in the units digit. That's 10 8's.Each of the numbers 80, 81, ... 89 has an 8 in the tens digit. That's 10 more 8's.(You could do this yourself just by writing down all the numbers.)
There are 8*8 = 64 such numbers.
There are 9000 4 digit numbers Find 4 digit numbers that are all different from 1 find 4 digit numbers that are all different from 1 The thousands digit has 8 ways to choose, hundreds, tens, and units all have 9 ways => there are 8 x 9 x 9 x 9 = 5832 digits => 4 digit numbers contain at least 1 digit 1 = number of 4 digit numbers , the number of 4 digit numbers is different by digit 1 =9000 - 5832 = 3168 numbers
The first 8 digit number is 10,000,000, the last is 99,999,999 which means there are 90,000,000 8 digit numbers
90
none
-5
57
You can make 4*3*2/2 = 12 numbers.
512