1 、 Did you know? In the decimal number system （ base 10) ten different digits, 0 to 9, are used to write all the numbers。 In the binary number system （base 2） two different digits are used， i.e. 0 and 1.Which one of the following numbers is not a valid number in the octal number system （base 8)?A） 128 B） 127 C） 126 D） 125 E) 1242、The number of diagonals that can be drawn in a regular polygon with twenty sides (icosagon) is_____.3、If a and b are integers, 10?？3=1，152??7=3, and then 379??6 is equal to_____。4、Two numbers are in the ratio 2 ： 3。 When 4 is added to each number the ratio changes to 5 ： 7.The sum of the two original numbers is____。5、The greatest number of Mondays which can occur in 45 consecutive days is____6、Saul plays a video game in which he scores 4 for a hit and lost 6 for a miss 。 After 20 rounds his score is 30. The number of times he has missed is____.7、Three girls A, B and C run in a 100 m race. When A finishes, B is 10 m behind A and when B finishes C is 20 m behind B. How far in metres was C from A when A finished？(Let’s assume all the athletes run at a constant speed）8、The areas of the faces of a rectangulabox are 84 cm2 , 70 cm2and 30 cm2。The volume of the box in cm3 is____.9、You have 3 weights： 1 kg， 3 kg and 9 kg as well as an equal arm balance, as shown。 How many different weight objects can you weigh with these three?[Remember the weights may be placed on either side］参考答案：1、A 考察我们学过的简单的进制问题，显然 8 进制中没有 8 出现 2、170 找规律，公式为 n×(n-3）÷23、1 定义新运算,就是求 379÷6 的余数。 4、40,16 和 24 5、7 6、57、28 米，根据距离比求出速度比,三者的速度比为 1：9/10：18/25 8、420 分解质因...
