How many times does 5 go into 10? The answer is 2 because 5 times 2 = 10.
Add on a zero and you have the final answer be 20
So 100 divided by 5 is 20
If you had 100 cookies and 5 friends, then each friend gets 20 cookies (no leftovers)
You can visualize it having 5 rows of 20 cookies per row, or 20 rows of 5 cookies per row, ultimately leading to 20 times 5 = 100 total.