# How do you find an equation that describes the sequence 11, 22, 33, 44,... and find the 25th term?

Feb 20, 2017

$275$

#### Explanation:

Sometimes you can spot the pattern strait away. Other times not.

Let the term count be $i$
Let the ith term be ${a}_{i}$

I have made the following connection:

${a}_{1} \to 1 \times 11 = 11$
${a}_{2} \to 2 \times 11 = 22$
${a}_{3} \to 3 \times 11 = 33$
${a}_{4} \to 4 \times 11 = 44$

Thus it follows that:

${a}_{25} \to 25 \times 11 = 275$