Excell formula

Hello, i am trying to find a formula so that if i put a value in cell a2 and a valu

e in cell a3 then i want in cell a1 it to produce a value eg a1 will be the total a2 1 was sold which would have a value of £80 and a3 2 was sold so it will produce a value of £200 so a1 would total £280, but i need this to work with increasing numbers so if cell a3 value was 10 and a2 was 1 the vale in a1 would be 1080. any help would be great i have been trying this for 4 day's

thanks

simon