The sum of the first \(n\) terms of an arithmetic progression (AP) can be found using the formula:

\(S_n = \frac{n}{2} \cdot (a + l),\)

where:

- \(S_n\) is the sum of the first \(n\) terms,

- \(n\) is the number of terms,

- \(a\) is the first term,

- \(l\) is the last term.

Given that \(S_n = 252\), \(a = -16\), and \(l = 72\), we can substitute these values into the formula:

\(252 = \frac{n}{2} \cdot (-16 + 72).\)

Simplify the expression inside the parentheses:

\(252 = \frac{n}{2} \cdot 56.\)

Now, divide both sides of the equation by 56:

\(\frac{252}{56} = \frac{n}{2}.\)

Simplify the left side:

\(4.5 = \frac{n}{2}.\)

Now, multiply both sides by 2 to solve for \(n\):

\(n = 2 \cdot 4.5 = 9.\)

Therefore, the number of terms in the arithmetic progression is 9.