请教gwd 一道数学题

if k is a positive integer ,what is the ramainder when 2^k is divided by 10?

(1)k is divisible by 10

(2)k is divisible by 4

key:B

 个人认为选d 因为a也可以啊 如2^10尾数为4 2^20尾数也为4 啊 那除10后 尾数也应该是4 是可以确定的  请教NN

if m is the least common multiple of 90,196,300 ,which of the following is Not a factor of m?

 a, 600  b 700 c 2100 d 4900 e 900  key:a

least common multiple 是2x45x98x150 =2^3x3^3x5^3x7^2 600也可以是他的fator啊

公倍数算错了，应该是2^2×3^2×5^2×7^2＝44100

3q