1。 What is divisible by both 5 and 2 is a multiple of 10, so 10 =10 (where 100 is10), and a * * divisible by 5 is/.

2 Since the multiple of 2,3,5 is 30, that is, the least common multiple of 2,3,5 is 30, then all those that meet the requirements are 30n, so 30n >；: = 100, then n >; =3.3, so the minimum n is 4, so it is 120.

3, the minimum factor is 1, and the maximum is 36.

4 let this decimal be x,

Then from the topic 100x-x=25, so x=25/99.

53b

Let the length of a rectangle be x, then we can know that (X-4) 2 = X (X-4)-20, so x=9, that is, the area of the rectangle is 45.

7, the surface area is equal to the area of the original cuboid+the area increased by these two faces, and the maximum is formed when the two faces are 6*5.

2(6*5+6*4+4*5)+2*6*5=208

8.6 times

9 * * * has 1000 block, so the length is1000 * 0.1m =100m.

10, 18

1 1，30n，30