Counting by \(5\)s means going up by 5 each term instead of by \(1\).

Here is usual counting: \[1,2,3,4,\dots\]

Here is counting by \(5\)s: \[5,10,15,20,\dots\]

In regular counting by \(1\)s you can start from any number. Here is counting by \(1\)s starting from \(8.\) \[8,9,10,11,12,13,\dots\]

Here is counting by \(5\)s starting from \(8.\) Each term goes up by \(5.\) \[8,13,18,23,28,33,\dots\] Notice that every two-terms ends in the same number. In this example, the first, third, and fifth terms are numbers ending in \(8.\) The second, fourth, and sixth terms are numbers ending in \(3.\) This pattern always happens when counting by \(5\)s.