You have two cups one is 6cm and other 10cm with no measurement and you have to pour 8cm of water into the 10cm cup using the two cup, without measuring it. How can you?

Here's one way to do it.

1. Fill the 6 cm cup.

2. Pour its contents into the 10 cm cup. This leaves 4 cm yet to be filled.

3. Refill the 6 cm cup and use it to fill the 10 cm cup. This leaves 2 cm in the 6 cm cup.

4. Empty the 10 cm cup and add the 2 cm from the 6 cm cup.

5. Refill the 6 cm cup.

6. Pour its contents into the 10 cm cup.

The 10 cm cup now contains 8 cm of water.