AMC10 2024 B
AMC10 2024 B · Q8
AMC10 2024 B · Q8. It mainly tests Primes & prime factorization, Counting divisors.
Let $N$ be the product of all the positive integer divisors of $42$. What is the units digit
of $N$?
设 $N$ 是 $42$ 的所有正整数除数的乘积。$N$ 的个位数是多少？
(A)
0
0
(B)
2
2
(C)
4
4
(D)
6
6
(E)
8
8
Answer
Correct choice: (D)
正确答案：（D）
Solution
The factors of $42$ are $1, 2, 3, 6, 7, 14, 21, 42$. Multiply the unit digits to get $\boxed{\textbf{(D) } 6}$
$42$ 的因数是 $1, 2, 3, 6, 7, 14, 21, 42$。将个位数相乘得到 $\boxed{\textbf{(D) } 6}$
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