It's in the form of fractions 1/4×5+1/5×6+1/6×7+…… 1/39×40

It's in the form of fractions 1/4×5+1/5×6+1/6×7+…… 1/39×40

1/4×5+1/5×6+1/6×7+…… 1/39×40
=(1/4-1/5)+(1/5-1/6)+(1/6-1/7)+.+(1/39-1/40)
=1/4-1/5+1/5-1/6+1/6-1/7+.+1/39-1/40
=1/4-1/40
=9/40

24 6 2 4 7, 24 6 8, 1 1 3 4, 5 1 1 3, 8 4 4 6, 4 4 6 9, 6 8 8 9, 5 7 7 7, 4 5 10, 9 1 8 8
2 2 6 9,3 3 7 10,4 5 9 9 ,7 8 8 10,4 9 9 9,7 8 8 8,3 4 9 9,3 4 10 10,7 5 6 9,

7-4 = 36 + 2 = 82 * 8 * 6 / 41 + 1 = 22 * 3 * 43 + 1 = 45 + 1 = 68 + 4 = 126-4 = 29-6 = 34 + 4 = 85777 no solution 4 - (5-10) * 49188 no solution (6 / 2 + 9) * 433710 no solution (9 / 9 + 5) * 48 * 10-7 * 84999 no solution 7888 no solution (9 + 9) / 3 * 43 * 10 + 4-106 - (5-7) * 9

How to calculate 35 × 24

=35×2×12
=70×12
=840

Which two sentences does 25.15.21.1.18.5.16.9.7.9.12.15.22.5.25.15.21 stand for? Two sentences!

25 15 21 1 18 5 16 9 7 ,

Well, I see

7 out of 3 vs 21 out of 5
15 / 4 vs 25 / 4
32 vs. 0. 8
1 to 0.25
35 vs. 9. 25

7/3:21/5
=7/3×5/21
=5:9
15/4:25/4
=15/4×4/25
=3:5
0.32:0.8
=32:80
=2:5
1:0.25
=100:25
=4:1
1.35:9.25
=135:925
=27:185

How easy is it to multiply 88 by 3 / 89?

88 × 3 / 89
=(89-1) × 3 / 89
=89 × 3 / 89 - 1 × 3 / 89
=3-3 / 89
=89 2 / 86

Simple calculation of 1998 / 1998 and 1998 / 2000 + 1 / 2001

1998 / 1998 and 1998 / 2000 + 1 / 2001 = 1 / (1 + 1 / 2000) + 1 / 2001 = 1 / (2001 / 2000) + 1 / 2001
=2000/2001+1/2001=1

How to calculate? How many times can we get to 100W
For example, how many times does 1,2,4,8 (4 times = 15) equal to 100W

This is an equal ratio sequence, and each general expression can be written as 2 ^ (n-1)
2^(n-1)＞1000000
When n = 21, 2 ^ 20 = 1048576
So when you count 21 times, you can get 100W

Observe the following formula: 2 ^ 1 = 2, 2 ^ 2 = 4, 2 ^ 3 = 8, 2 ^ 4 = 16, 2 ^ 5 = 32, 2 ^ 6 = 64, 2 ^ 7 = 128, 2 ^ 8 = 256
According to the above rule, what do you think is the last digit of 2 ^ 20?

2,4,8,6 repeat, 20 / 4 is the whole, so it is 6