Yields on short$-$term bonds tend to be more volatile than yields on long$-$term bonds. Suppose that you have estimated that the yield on $20-$year bonds changes by $7\mathrm{.}5$ basis points for every $20\mathrm{.}25-$basis$-$point move in the yield on $5-$year bonds. You hold a $$1\mathrm{.}2$ million portfolio of $5-$year maturity bonds with modified duration $4$ years and desire to hedge your interest rate exposure with T$-$bond futures, which currently have modified duration $9$ years and sell at F$0=$ $$80.$ How many futures contracts should you sell?

Note: Do not round intermediate calculations. Round your final answer to the nearest whole number.

I tried the answers $2$ and $18,$ both of which were wrong. I don$$t know how to calculate them. An expert$$s reply of $667$ is also wrong.