Palak has two ribbon rolls of lengths 60 cm and 80 cm. She wants to cut them into pieces of equal length such that there is no ribbon left at the end. Find the greatest possible length of each piece.

To solve this problem, we need to find the greatest possible length of each piece that can divide both ribbon rolls completely without any leftover. This means we are looking for the greatest common divisor (GCD) of the two lengths.

Here are the steps to find the GCD:

List the factors:
- First, list all the factors of each ribbon's length.
- For 60 cm: The factors are 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, and 60.
- For 80 cm: The factors are 1, 2, 4, 5, 8, 10, 16, 20, 40, and 80.
Find common factors:
- Compare the lists of factors to determine which factors are common to both numbers.
- The common factors are 1, 2, 4, 5, 10, and 20.
Identify the greatest common factor (GCD):
- From the common factors, identify the largest one.
- Among 1, 2, 4, 5, 10, and 20, the greatest is 20.

Thus, the greatest possible length of each piece that Palak can cut from both ribbons, so that there is no ribbon left, is 20 cm.

Using this method, Palak can cut each ribbon into pieces that are each 20 cm long, ensuring each ribbon is divided evenly.