3/8x17 by using estimating product
3/8 of 16 is close enough. That would be 6.
For the exact answer, add 3/8 of 1, giving you 6 3/8.
All of these questions you are posting are basically the same. Read the helpful material at the following web site and try to do them yourself.
http://www.glencoe.com/sites/common_assets/support_pages/ca_mac1_sg_chapter07.pdf