last digit
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Find the last digit of 7^2013
Consider the first 8 calculations of 7 to an exponent: 7^1 = 7 7^2 = 49 7^3 = 343 7^4 = 2,401 7^5 = 16,807 7^6 = 117,649 7^7 = 823,543 7^8 = 5,764,801 Take a look at the last digit of the first 8 calculations: 7, 9, 3, 1, 7, 9, 3, 1 The 7, 9, 3, 1 repeats through infinity. So every factor of...- math_celebrity
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Given that m is a positive integer and 4^m - 1 = n, which of the following values CANNOT represent n
A. 3 B. 7 C. 63 D. 255 We know that: 4^1 = 4 4^2 = 16 4^3 = 64 4^4 = 256 4^5 = 1024 4^6 = 4096 Notice they all end in 4 or 6. This continues for to infinity. 4^m will either end in a 4 or a 6 Therefore, 4^m - 1 ends in: 4 - 1 = 3 6 - 1 = 5 Choices A, C, and D end in 3 or 5. Choice B...- math_celebrity
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- exponent last digit
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