Standard deviation challenge

I’m getting a different answer than the one in the video. I think I’m misunderstanding something because I got the same answer twice. Here’s the math I did.
{ 1, 2, 3, 4, 4, 4, 7, 10 }

Sum of data:35
Mean of data:4.375

For differences I took each data entry and subtracted the mean. Then I took each difference and squared it. Then added them together. For example:
1- 4.375 = -3.375
-3.375 ^ 2 = 11.390625

Sum of differences squared:57.875 This number was different from the video
Divided by 7 is 8.267857143
Square root of that is 2.875388173 which was my answer for the standard deviation.

Not sure where I went wrong but hopefully the rest of the math would have been right even if I got a different sum of differences squared.