How to find an area under a curve within Simulink

Hi guys, I've devloped a rough motorcycle model and have produced a RPM vs Time graph as seen in the images. Can someone please tell me the most straight forward way to find the area under the curve in the graph. Just from looking at it i've estimated the value to be around 20,000,000m^2 but any integration methods i've trialled arent giving me anything clos to that answer.

Cheers, Ollie.

[Fangjun Jiang]

around 20,000,000? How come? I see roughly 4000*6.7=26800

[oliver shelley]

Well that's embarrasing! I've mis-read the graph I'm using. This now makes my integration techniques correct. Sorry for wasting anyones time.