How many zeros are there at the end of the product 1 by 2 by 2 by 3 by 4. By 99 by 100? Have a formula!

How many zeros are there at the end of the product 1 by 2 by 2 by 3 by 4. By 99 by 100? Have a formula!

If a 2 and a 5 are multiplied by 10, there will be a zero (10,20 can also be regarded as the product of 2 and 5 and multiplied by a number), so we can see how many zeros there are when we multiply 2 and 5. But the number of numbers containing 5 is less than 2, so we can see how many 5.5,10,15,20,25,30,35,40,45,50,55,60,6 can be decomposed from all numbers

The area ratio of two similar triangles is 4; 9. If the height of one side of one triangle is 6, the height of the corresponding side of the other triangle is -——

According to the ratio of areas equal to the square of the similarity ratio, the
√ 4: √ 9 = 6: H or √ 4: √ 9 = H: 6
2: 3 = 6: H or 2:3 = H: 6
H = 9 or H = 4
The height of the other triangle is 4 or 9

Solution equation: (1 + 2 / 5) x = 240 solution equation: (120-x) × 1 / 5 = 8 × 3 / 4

（1+2/5）x=240
7x/5=240
7x=1200
x=1200/7
(120-x)×1/5=8×3/4
(120-x)×1/5=6
120-x=30
x=120-30
x=90

A semicircle has a diameter of 10 decimeters, a perimeter of and an area of

A semicircle is 10 decimeters in diameter, 25.7 decimeters in circumference and 39.25 square decimeters in area
10×3.14÷2 +10
=15.7 +10
=25.7 decimeter perimeter
5×5×3.14 ÷2
=78.5 ÷2
=39.25 square decimeters

18 - (10.6-9.52) simple calculation

（2.18+9.52）-10.6=11.7-10.6=1.1

In △ ABC, ∠ B = 90 °, ad is the bisector of ∠ BAC, DF ⊥ AC is f, de = DC, then be = CF?
I want it before 10:5! I'm so lucky!

It is proved that ad is the bisector of ∠ BAC, and BD ⊥ AB, DF ⊥ AC, so BD = DF and de = CD, and both triangles are right triangles. So be = CF

There are 2013 straight lines on the plane, A1 ⊥ A2, A2 ⊥ A3, A3 ∥ A4, A4 ∥ A5, A5 ⊥ A6, A6 ⊥ A7 What is the positional relationship between A2 and a2013?

A1 is parallel to A5, A5 is parallel to a923456789. It circulates all the time, so A1 is parallel to a2013, A1 is vertical to A2, so A2 is vertical to a2013

If the sum of the top and bottom of the isosceles trapezoid ABCD is 4, and the acute angle between the two diagonals is 60 degrees, what is the area of the isosceles trapezoid

There are two cases: the upper bottom is a, the lower bottom is 4-A, and the acute angle between the diagonals is 60 degrees

LG (x + y) + LG (2x + 3Y) - Lg3 = LG4 + lgx + lgY find the ratio of X to y
How does LG4 + lgx + lgY turn into 12xy

lg(x+y) + lg(2x+3y) - lg3= lg4+lgx+lgy
lg(x+y)+ lg(2x+3y) = lg3 +lg4+lgx+lgy
lg[(x+y)*(2x+3y)] = lg[ 3*4*xy)
(x+y)(2x+3y)=12xy

Xiaolan's room is 3.5 meters long, 3 meters wide and 3 meters high. Except for the 4.5 meters of doors and windows, the walls and roofs of the room are pasted with wallpaper. How much wallpaper does this room need?

3.5 × 3 + 3.5 × 3 × 2 + 3 × 3 × 2-4.5 = 10.5 + 21 + 18-4.5 = 45 square meters; a: this room needs at least 45 square meters of wallpaper