# What is the sum of a 24–term arithmetic sequence where the first term is 12 and the last term is 219?

Sum $= 2772$

#### Explanation:

Given $n = 24 , {a}_{1} = 12 , {a}_{24} = 219$

Formula for Sum of Arithmetic Sequence:

${S}_{n} = \frac{n}{2} \left({a}_{1} + {a}_{n}\right)$

${S}_{24} = \frac{24}{2} \left(12 + 219\right)$

${S}_{24} = 12 \left(231\right)$

${S}_{24} = 2772$