[計量] 請問Q1-2&1-3
想請問Q1-2的20題
the "reflection" of a positive integer is obtained by
reversing its digits. For example,321 is the reflection and is the reflection
of 123. The difference between a five-digit integer and its reflection must
be devisible by which of the following?
a. 2
b. 4
c. 5
d. 6
e. 9
答案是e
請問這題要如何判斷呢? 因為用帶的似乎不可行
與Q1-3的30題
If x and y are prime numbers, which of the following cannot be the sum of
x and y?
a. 5
b. 9
c. 13
d. 16
e. 23
這個我是用帶得求出答案,想請問高手有別的解法嗎 謝謝
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