+0

0
185
3
+30

Find the remainder when $3 \times 13 \times 23 \times 33 \times \ldots \times 183 \times 193$ is divided by $5$.

Apr 24, 2019

#1
0

product(3, 13, 23 , 33 , 43 , 53 , 63 , 73 , 83 , 93 , 103 , 113 , 123 , 133 , 143 , 153 , 163 , 173 , 183 , 193)  mod 5

= 1

Apr 25, 2019
#2
+23321
+2

Find the remainder when $$3 \times 13 \times 23 \times 33 \times \ldots \times 183 \times 193$$ is divided by $$5$$.

$$\begin{array}{|rcll|} \hline 3 \pmod{5} &\equiv& 3 \\ 13 \pmod{5} &\equiv& 3 \\ 23 \pmod{5} &\equiv& 3 \\ 33 \pmod{5} &\equiv& 3 \\ \ldots \\ 183 \pmod{5} &\equiv& 3 \\ 193 \pmod{5} &\equiv& 3 \\ \hline \end{array}$$

$$\begin{array}{|rcll|} \hline && \mathbf{3 \times 13 \times 23 \times 33 \times \ldots \times 183 \times 193 \pmod{5}} \\ &\equiv& 3 \times 3 \times 3 \times 3 \times \ldots \times 3 \times 3 \pmod{5} \\ &\equiv& 3^{20} \pmod{5} \quad | \quad 3^2\pmod{5} \equiv 9 \pmod{5} \equiv -1 \pmod{5} \\ &\equiv& \left(3^2\right)^{10} \pmod{5} \\ &\equiv& \left(-1\right)^{10} \pmod{5} \\ & \mathbf{\equiv}& \mathbf{1 \pmod{5}} \\ \hline \end{array}$$

The remainder is 1

Apr 25, 2019
#3
+30
0

Thanks!

er1004  Apr 25, 2019