Again, until the start of TAMa itself, https://cms.noi.ph/ leads to the TAMa Practice Round where you can test your answers using the contest interface.
You can also check the correctness of your solutions by comparing them against the answers here. During the actual contest, an automated checker will handle this step.
Sum of Sum of Odds: Answers
Mod Powers: Answers
Summer SEMs: Answers
First, almost all TAMa problems involve modulo because of the size of the numbers involved. You can refer to a quick crash course in modular arithmetic here.
Second, the solution sketches detail solutions for all four subtasks in order to 1) let the necessary ideas build on one another naturally, and 2) emphasize that despite later subtasks being possibly quite difficult, it should still be possible to earn points in earlier subtasks using basic mathematics and programming.
We don’t expect you to implement four programs, one for each subtask. Usually, the most efficient program which solves the final subtask can also just be used to solve the other subtasks as well.
Sum of Sum of Odds: Solution
Mod Powers: Solution
Summer SEMs: Solution