Microsoft's exam questions (mathematics)

The topic is as follows, I hope you can solve the answer 1, 1000! There are several digits, why 2, F=1 n>8 n<12 F=2 n<2 F=3 n=6 F=4 n=other Use + - * / and the sign function combines the F function sign=0 n=0 sign=-1 n<0 sign=1 n>0 3. Program a program to find the sum of prime numbers such as F=1+3+5+7 +11+13+17=58