9
about 1,0000000000000
To find how many 4-digit numbers equal 19, we need to consider all combinations of four digits (ranging from 0 to 9) that add up to 19. However, since the maximum sum of four digits (9 + 9 + 9 + 9) is 36, the possible combinations are limited. There are no valid 4-digit numbers where the sum of the digits equals 19 while ensuring that the first digit is not zero. Therefore, the answer is that there are no valid 4-digit numbers that equal 19.
A 4-digit number can range from 0000 to 9999, which includes all combinations of four digits. Since each digit can be any number from 0 to 9 (10 options), the total number of combinations is calculated as (10^4). Therefore, there are 10,000 different combinations for a 4-digit number.
Only one.
To form three-digit even numbers from the set {2, 3, 5, 6, 7}, we can use the digits 2 or 6 as the last digit (to ensure the number is even). For each case, we can choose the first two digits from the remaining four digits. For three-digit numbers, there are 2 options for the last digit and (4 \times 3 = 12) combinations for the first two digits, resulting in (2 \times 12 = 24) even numbers. For four-digit even numbers, we again have 2 options for the last digit. The first three digits can be selected from the remaining four digits, giving us (4 \times 3 \times 2 = 24) combinations for each last digit. Thus, there are (2 \times 24 = 48) even four-digit numbers. In total, there are (24 + 48 = 72) three-digit and four-digit even numbers that can be formed from the set.
45 In combinations, the order of the digits does not matter so that 12 and 21 are considered the same.
Twelve in all: One of 4 digits, Three of 3 digits, Four of 2 digits, Three of 1 digit, and One with no digits. In mathematical terms, the last IS a combination, but in common usage, probably not.
If you use them only once each, you can make 15 combinations. 1 with all four digits, 4 with 3 digits, 6 with 2 digits, and 4 with 1 digit. There is also a combination containing no digits making 16 = 24 combinations from 4 elements.
Assuming the digits cannot be repeated, there are 7 combinations with 1 digit, 21 combinations with 2 digits, 35 combinations with 3 digits, 35 combinations with 4 digits, 21 combinations with 5 digits, 7 combinations with 6 digits and 1 combinations with 7 digits. That makes a total of 2^7 - 1 = 127: too many for me to list. If digits can be repeated, there are infinitely many combinations.
64
There are 167960 9 digits combinations between numbers 1 and 20.
If the 6 digits can be repeated, there are 1296 different combinations. If you cannot repeat digits in the combination there are 360 different combinations. * * * * * No. That is the number of PERMUTATIONS, not COMBINATIONS. If you have 6 different digits, you can make only 15 4-digit combinations from them.