The first digit can be one of {1, 2, 3, 4, 5, 6, 8}, ie one of 7 digits;
for each of these, the second digit can be one of {0, 1, 2, 3, 4, 5, 6, 8}, ie one of 8 digits;
for each of these two, the third digit can also be one of {0, 1, 2, 3, 4, 5, 6, 8}, ie one of 8 digits;
making 7 × 8 × 8 = 488 such three digit numbers.
90
4,536 whole numbers or mixed numbers. 5,040 pure decimals.
24
There are 5 digits in 24680; think of them as 5 compartments. You can select 5 numbers for the 1st compartment, 4 numbers for the 2nd compartment, 3 numbers for the 3rd compartment, 2 numbers for the 4th compartment, and 1 number for the 5th compartment. So, the answer is 5*4*3*2*1 or 5! or 120
In case of digits or numbers, when we say combination, since the order of the numbers matters, we really need to find the permutations. For example, 12 and 21 are two permutations and not combination. The permutation for 10 digits chosen 5 ways is 10*9*8*7*6, which is 30240. But how many are there in whole like four digit has 24.
there are 899 whole numbers that have three digits.
there are 89 twodigits in whole numbers
how many numbers exactly have 4 digits ? 8900, 8999, 9000, 9999
10,000
90
89999 Any whole number above 99999 has 6 or more digits, and any whole number below 10000 has 4 or less digits. Since there are only whole numbers involved, it is a simple subtraction of 10000 from 99999.
890
I believe here are 51 such numbers.
180
4,536 whole numbers or mixed numbers. 5,040 pure decimals.
There are no 3-digit whole numbers whose digits sum to 3. The smallest 3-digit number is 100, and the largest is 999, but in neither case is the sum of the digits equal to 3.
999 are whole.