Think about multiplication as having piles of rocks. $6*24$ represents 6 piles of 24 rocks.
Now what happens if you split each pile in two halves? The number of rocks in your pile half, but the number of piles double. Thus, you get 12 piles of 12 rocks, or $12*12$.
You didn't change the number of rocks, you only rearrange them in a different way. Thus you have $6*24=12*12$ rocks.
And the same holds with any numbers. If you split each pile in halves, the number of rocks in piles half, and the number of piles double. But in total you have the same number of rocks... Thus, if you multiply two numbers, half one and double the other, you get the same product. [Note that this intuitive explanation works for whole numbers, but can also be made to work easily for fractions].