请教几道数学题目~~~模考软件里的

laura1019

1. In a certain deck of cards, each card has a positive integer on it. In a multiplication game, a child draws a card and multiples the integer on the card by the next larger integer. If each possible product is between 15 and 200, then the least and greatest integers on the cards could be_________.

答案是 4 and 13,怎么算的捏~~

2.For every positive even integers n, the function h(n) is defined to be the product of all the even integers from 2 to n, inclusive, if p is the smallest prime factor of h(100)+1, then p is _____.
答案是 greater than 40

3. 还有关于work problem,每次做题都会困惑。。。有没有什么好的思路呢？

各位NN们，请解答，谢谢啦！

wyw1018

1、两个连续正整数之积在15-200范围
3×4=12 小于15 4×5=20 大于15 在范围内；14×15=210 超出范围，13×14=182 范围内，所以4和13
2、h（100）=2×4×...×98×100，里面最大的质因子为47（94/2）且从2到47的质因子都在其中
    h（100）+1与h（100）为连续正整数，因此互质，则h（100）+1不能有从2到47的质因子，因此最小质因子必大于47

laura1019

SOGA  非常感谢~~