For any real numbers \(a\), \(b\), and \(c\)
$$\left( {a \times b} \right) \times c = a \times \left( {b \times c} \right)$$
If you multiply three numbers together, the product will be the same no matter how you group the numbers.
Suppose, we are given the following values
$$\displaylines{
a = 4 \cr
b = 2 \cr
c = 7 \cr} $$
We plug them into the "formula"
$$\left( {a \times b} \right) \times c = a \times \left( {b \times c} \right)$$
We have
$$\displaylines{
\left( {4 \times 2} \right) \times 7 = 4 \times \left( {2 \times 7} \right) \cr
8 \times 7 = 4 \times 14 \cr
56 = 56 \cr} $$
Great! The left side and the right side of the equation do have the same result. They have the same product of \(56\).