Parent Paper size is (11.69 inches x 16.54 inches) Child paper size is (2 inches x 3 inches)
How many divisions could be made from the parent size so that minimum paper gets wasted.
I need some formula to solve this problem, so as to apply that in Microsoft Excel.
I want to cut paper in such a size so that minimum paper gets wasted.
I'm assuming you are looking for a way to take a rectangular $11.69$ inch by $16.54$ inch paper and cut it into as many as possible rectangular $2$ inch by $3$ inch pieces.
Here I is what I believe is the solution, as shown above. In cases like this, it's generally helpful to use the smaller dimension as the restraining factor. Using the width, i.e., $11.69$ inches, you can have $3$ child paper ones placed side by side using their $3$ inch dimensions, with $8 \times 3 = 24$ of them by repeating this $8$ times down the height, using $8 \times 2 = 16$ inches of the height.
Next, you can then use $2$ inches of the remaining parent page width for placing a child page, and repeating this $5$ times down the parent page's height, using a total of $5 \times 3 = 15$ inches of the height.
In total, you can then cut $24 + 5 = 29$ child pages. The total area of the parent page is $11.69 \times 16.54 \approx 193.35$ square inches. You would have then used $29 \times 2 \times 3 = 174$ square inches. This leaves only just under $20$ square inches of waste.