4+4+4+4+4= 20
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To find the number of 5-digit combinations from 1 to 20, we first calculate the total number of options for each digit position. Since the range is from 1 to 20, there are 20 options for the first digit, 20 options for the second digit, and so on. Therefore, the total number of 5-digit combinations is calculated by multiplying these options together: 20 x 20 x 20 x 20 x 20 = 3,200,000 combinations.
There are 167960 combinations.
To calculate the number of 4-digit combinations using the digits 1, 3, 5, and 7 exactly once each, we can use the permutation formula. There are 4 choices for the first digit, 3 choices for the second digit, 2 choices for the third digit, and 1 choice for the fourth digit. Therefore, the total number of combinations is 4 x 3 x 2 x 1 = 24. So, there are 24 possible 4-digit combinations using the digits 1, 3, 5, and 7 exactly once each.
To calculate the number of combinations of 5 numbers possible from 1 to 20, we use the formula for combinations, which is nCr = n! / (r!(n-r)!). In this case, n = 20 and r = 5. Plugging these values into the formula, we get 20! / (5!(20-5)!) = 20! / (5!15!) = (20x19x18x17x16) / (5x4x3x2x1) = 15,504 possible combinations.
There are 6C3 = 20 such combinations.