$$6$$ * $$5 = (6+5+4+3+2+1) \times 5 = 21\times 5 = 105$$. 
Kangaroo came up with a new operation * for positive integers. He gave a few examples as shown below:  $$2$$ * $$3$$$$=\left( 2+1 \right)\times 3=9$$;  $$4$$ * $$2$$$$=\left( 4+3+2+1 \right)\times 2=20$$;  $$3$$ * $$5$$$$=\left( 3+2+1 \right)\times 5=30$$.  What is the value of the expression $$6$$ * $$5$$ ? 
Options:
1. $$30$$ 
2. $$90$$ 
3. $$105$$ 
4. $$210$$ 
5. $$315$$ 