One pattern that you can see in a multiplication table is the perfect square numbers. It runs from the top left hand corner directly through the middle to the bottom right hand corner. A perfect square is a number that is multiplied by itself. The perfect square numbers are 1, 4, 9, 16, 25, 36, 49, 64, 81, 100, 121, 144. They keep going forever on but those are the main ones from 1x1 to 12x12.
The formula for the light bend would be n1*sin i= n2 * sin r
If you use "sin (90-x)= cos x" principle, you can change the sin in the equation into
n1*sin i= n2 * sin r
n1 * cos a= n2 * cos b
n2/n1= cos a/ cos b
Assuming the n constant is the ratio of the glass compared to water then the answer would be: cos a/ cos b