And what's 49 squared? Well, you know 50 squared is 2,500, so you know it's going to be close to that, so you can already make a pretty good estimate that it's going to be d. But if you wanna multiply it out, we can. 49 times 49, nine times nine is 81. Nine times four is 36, plus eight is 44. Four times nine, 36. Four times four is 16 plus three, we have 19. And then you add all of that together, and you indeed do get, so that's 10.