Look at the diagram below which shows one and 1/4 of a rectangle shaded.
That is one whole rectangle and 1⁄4 of a rectangle.
Let's multiply one and 1/4 by 4.
This will give 4 lots of one and 1⁄4.
1 1/4+ 1 1/4 + 1 1/4 + 1 1/4 = 4 4/4
4 4/4 is the same as 5 wholes.
This is shown by the diagrams below.
4 x 1 and 1/4 = 5.