Practicing Success
Practicing Success
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What is the remainder when \( { 2 }^{ 20 } \) is divided by 7? |
4 3 2 5 |
4 |
By Fermat's theorem \( { 2 }^{ 7-1 } \) ≡ 1 (mod 7) \( { 2 }^{ 6 } \) ≡ 1 (mod 7) \( { 2 }^{ 18 } \) ≡ 1 (mod 7) \( { 2 }^{ 20 } \) ≡ 4 (mod 7) |
