10. What is the remainder when $2^{2} \times 3^{3} \times 5^{5} \times 7^{7}$ is divided by 8 ?
A 2
B 3
C 4
D 5
E 7
10. C $2^{2} \times 3^{3} \times 5^{5} \times 7^{7}$ is of the form $2^{2} \times$ an odd number. It therefore has the form $4(2 n+1)=8 n+4$ where $n$ is a positive integer and so leaves a remainder of 4 when divided by 8 .