When the expression (7^1)(7^2)(7^3) ... (7^100) is written as an integer, what is the product of the tens digit and the ones digit?
+36 To find the power of the full expression, we can find the sum of the numbers from 1-100. So, using the Gauss Formula:
n(n+1)/2
100(101)/2
10100/2
5050
We can then find patterns, since we are trying to find the tens and ones digits.
7^1 = 07
7^2 = 49
7^3 = 343
7^4 = 2401
7^5 = 16807
7^6 = 11649
7^7 = 823543
Use the pattern to solve the answer. Hope this helps!
Let me know if I did anything wrong!
