When we arrange the numbers in such an order that it starts from the smallest number and goes towards the largest number, that order is called ascending order.
Prime factors of 63 are : 3, 3, 7
As 3 repeats and 3 is smaller than 7 so, when we write this in ascending order as the product of these, we write in such a way;
63 = 3 x 3 x 7 = 3² x 7
Now 3² = 9 and 9 is greater than 7,so,
63 = 7 x 9