23、Expression: $1^{2015}+2^{2015}+3^{2015}+\cdots+2013^{2015}+2014^{2015}$, the unit digit of the calculation result is
Analysis: The unit digit of each term repeats in a cycle of 4 (a cycle of 4 is used here to ensure that the pattern of each number is consistent. Actually, the pattern of $4^{n}$ is $4, 6, 4, 6, 0$, which can be seen as $4, 6, 4, 6$ repeating. In short, it can be considered as a cycle of 4, which can be remembered as a conclusion.), since $2015 \div 4=503 \cdots \cdots 3$, the unit digit of the result of the original expression is the same as that of $1^{3}+2^{3}+3^{3}+\cdots+2013^{3}+2014^{3}$. According to the formula: $1^{3}+2^{3}+3^{3}+\cdots+2013^{3}+2014^{3}=\left[\frac{2014 \times 2015}{2}\right]^{2}$, this result is a multiple of 10, so the unit digit of the result of the original expression is 5.
Supplement: $1^{3}+2^{3}+3^{3}+\cdots+n^{3}=\left[\frac{n(n+1)}{2}\right]^{2}$