Thank you for the opportunity to help you with your question!

For these types of problems, the main thing is to notice a certain pattern. You can tell that the left-hand side goes up by one each time. To get the right hand side, you multiply the left-hand side by 'one more than the left hand side'.

2*3=6

3*4=12

4*5=30

etc....

So, once you get to 9, you just multiply it by 10 to get the right hand side.

9*10=90

Answer: 90

Please let me know if you need any clarification. I'm always happy to answer your questions.

Sep 7th, 2015

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