hello, I am taking advanced statistics but am really confused. I am doing an assignment interpreting two way anova. I am trying to do all the calculations manually and when I compare to the spss answers, they are slightly different.

For example, I calculated the mean of a1b1 and the manual value I got was 60.31, and SPSS got 66.2500 I am positive that the data was entered corretly.. So I want to ask, is this ok??? or it has to be exactly the same? Thank you so much for your help