If you want to "verify" the GraphPad output manually to prove it is correct, you can do so for a 2x2 table using the simplified Chi-Square formula:
and select the Contingency table type from the welcome dialog. chi square graphpad verified
As a long-time Prism user, I’ve learned that while GraphPad makes the test easy, it doesn't hand-hold you through the verification process. Here is how you ensure your Chi-Square results in GraphPad Prism are truly reliable. If you want to "verify" the GraphPad output
For the same 2x2 table, Prism also reports: Fisher's exact test (two-tailed) P = 0.0041 chi square graphpad verified