What does the expression 28 = 10 + 10 + 8 illustrate?

The expression 28 = 10 + 10 + 8 illustrates the composition of base ten numbers by breaking down the number 28 into its component parts using base ten units. In this case, the number is represented as the sum of two tens (which equals 20) and an additional eight, clearly demonstrating how the number is constructed from smaller, more manageable parts.

The expression showcases how numbers can be composed of various combinations of tens and ones, aligning with the concepts of place value system in base ten, where each digit's position holds different weight. This is crucial in understanding addition and the way values accumulate to form larger numbers, reinforcing the foundational knowledge of arithmetic and numerical representation in base ten.