Finding the number of terms in an arithmetic series may sound daunting, but it's actually quite simple. You just need to enter the numbers into the formula U = a + (n - 1) b and find the value of n, which is the number of terms. Know that U is the last number in the series, a is the first term in the series, and b is the difference or difference between adjacent terms.
Step
Step 1. Identify the first, second, and last terms in the series
Usually, questions like this give the first 3 or more terms, and the last term.
For example, your question looks like this: 107, 101, 95…-61. In this case, the first term is 107 and the last term is -61. You need all this information to solve the problem
Step 2. Subtract the second term from the first term to find the difference (b)
In the example problem, the first term is 107 and the second term is 101. To find the difference, subtract 101 by 107 and get -6.
Step 3. Use the formula U = a + (n - 1) b to find n.
Enter the last term (U ), the first term (a), and the difference (b). Count the equations until you get the value of n.