11.
If p is a positive odd integer, what is the remainder when p is divided by 4 ?
(1) When p is divided by 8, the remainder is
(2) p is the sum of the squares of two positive integers
怎么能从条件２推出结论？我只能用代入法．
18.
What is the hundredths digit of the decimal z ?
(1) The tenths digit of 100z is 2.
(2) The units digit of 1,000z is 2.
我觉得可以分别得出啊, 是零不是吗？ | 
