How many telephones connections may be allotted with eight digits from...
**Introduction**
The number of telephone connections that can be allotted with eight digits from the number 0 to 9 can be calculated using the concept of permutations and combinations. In this case, we have a set of 10 digits (0 to 9) and we need to select 8 digits to form a telephone number. Let's break down the solution into the following steps:
**Step 1: Understanding the Problem**
To find the number of telephone connections that can be allotted with eight digits, we need to determine the total number of possible combinations of 8 digits from the set of 10 digits (0 to 9).
**Step 2: Using Combinations**
In this problem, we need to use combinations instead of permutations. The reason is that the order of the digits does not matter in a telephone number. For example, 12345678 and 87654321 are considered the same telephone number.
**Step 3: Calculating the Number of Combinations**
To calculate the number of combinations, we can use the formula for combination:
nCr = n! / (r! * (n - r)!)
Where n is the total number of digits (10) and r is the number of digits to be selected (8).
Using this formula, we can calculate the number of combinations as follows:
10C8 = 10! / (8! * (10 - 8)!)
**Step 4: Simplifying the Calculation**
To simplify the calculation, we can use the factorial notation. For example, 10! can be written as 10 * 9 * 8 * 7 * 6 * 5 * 4 * 3 * 2 * 1.
Using this notation, the calculation becomes:
10C8 = (10 * 9 * 8 * 7 * 6 * 5 * 4 * 3 * 2 * 1) / ((8 * 7 * 6 * 5 * 4 * 3 * 2 * 1) * (2 * 1))
**Step 5: Simplifying the Calculation Further**
By simplifying the calculation further, we can cancel out common terms in the numerator and denominator:
10C8 = (10 * 9) / (2 * 1)
**Step 6: Final Calculation**
After simplifying the expression, we get:
10C8 = 45
Therefore, the number of telephone connections that can be allotted with eight digits from the number 0 to 9 is 45.
**Conclusion**
In conclusion, there are 45 possible telephone connections that can be allotted with eight digits from the number 0 to 9. This calculation is based on the concept of combinations, where the order of the digits does not matter.