1- 1/2+ 1/2* 1/3- 1/2* 1/3* 1/4+ 1/2* 1/3* 1/4* 1/5

Let the above formula =y

y * 5 = 5-5/2+5/[2 * 3]+5/[2 * 3 * 4]+ 1/[2 * 3 * 4]

Add with the original formula

6 * y = 6-3+ 1-[5- 1/5]/[2 * 3 * 4]= 4-[24/5]* 24 = 4- 1/5

y= 19/30

1234565432 1

12345432 10

123432 100

1232 1000

12 10000

100000

Looking vertically, the answer is =13717260631.

The square of 65438 +05 = 225 1 * 2 and finally add 25.

The square of 25 =625 2*3, and finally add 25.

The square of 35 = 1225 3*4 and 25 at last.

Very simple, the last two digits are 5 2 = 25, and the first digit is n*(n+ 1).

There are two kinds of balls in the box. The ratio of red ball to white ball is 14: 1 1. Momo walked into the box.

After adding four red squares, the ratio of red squares to white balls in the box is 16: 1 1. How many red balls were there in the original box? How many red prayers are there in the box now?

Solution: If there are 14X red balls, then there are 1 1X white balls, so.

( 14X+4): 1 1X = 16: 1 1

X=2

The original red ball 14*2=28 and the original white ball 1 1*2=22.

Existing red ball: 14X+4=32.