Formual that Multiplies 2 columns to give a percentace based on 2 criteria

Hello all

I've got a spreadsheet with 4 columns as follows

Date|Hour|Value1|Value2
19/12/1013|10:00|243|54
19/12/2013|10:00|234|52
19/12/2013|11:00|234|76

What I am trying to do is multiply sum of Value2 by sum Value1 when the date criteria and hour criteria match specifics.

If tried sumifs for selecting the multiple criteria but this will only sum 1 column and not let me multiply.

For example in the above if my criteria where Date: 19/12/2013 and Hour: 10 I'd want to add 52 & 54 then multiply by 243 and 234 so would get 4.5 for example.

Thanks