To make a fraction of any whole number we need to take into account their multiples, so for 5 we have that the multiplies are
[tex]\mleft\lbrace5,10,15,20,25,30,35,40,\ldots.\mright\rbrace[/tex]and they are multiplies because
[tex]\mleft\lbrace1\cdot5=5,2\cdot5=10,\text{ 3}\cdot5=15,\ldots.\mright\rbrace[/tex]So, to see 5 as a fraction we can write
[tex]5=\frac{10}{2}=\frac{15}{3}=\frac{20}{4}=\ldots.[/tex]