These are sample practice MCQs created for exam preparation. These are NOT official exam questions.
What is the units digit of 3^100 + 7^100?
Question:
What is the units digit of 3^100 + 7^100?
What is the units digit of 3^100 + 7^100?
Options
Answer: (B) 2
Explanation:
Units digits of powers of 3: 3,9,7,1,3,9,7,1... (period 4). 100 = 4×25, so 3^100 has units digit 1. Units digits of powers of 7: 7,9,3,1,7,9,3,1... (period 4). 100 = 4×25, so 7^100 has units digit 1. Sum = 1 + 1 = 2 units digit.
Explanation:
Units digits of powers of 3: 3,9,7,1,3,9,7,1... (period 4). 100 = 4×25, so 3^100 has units digit 1. Units digits of powers of 7: 7,9,3,1,7,9,3,1... (period 4). 100 = 4×25, so 7^100 has units digit 1. Sum = 1 + 1 = 2 units digit.
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