17.48×37-174.8×2.7 34.5×8.23-34.5+2.77×34.5 17.48×37-174.8×2.7 34.5×8.23-34.5+2.77×34.5

17.48×37-174.8×2.7 34.5×8.23-34.5+2.77×34.5 17.48×37-174.8×2.7 34.5×8.23-34.5+2.77×34.5

17.48×37-174.8×2.7 =17.48×(37-27)=174.8
34.5×8.23-34.5+2.77×34.5=34.5×(8.23-1+2.77)=34.5×10=345

7,17,27,37,47,57,67,77,87,97
Prime numbers have () and composite numbers have ()

Prime number is also called prime number. It refers to the number in a natural number greater than 1 which can not be divided by other natural numbers except 1 and the integer itself. In other words, a natural number with only two positive factors (1 and itself) is a prime number
Composite numbers: numbers larger than 1 but not prime numbers are called composite numbers
Prime numbers have (7,17,37,47,67,97) combined numbers have (27,57,77,87)

2 17 37 77…… General term formula

7
17=7+10=7+10*2^0
37=17+20=17+10*2^1=7+10*2^0+10*2^1
77=37+40=37+10*2^2=7+10*2^0+10*2^1+10*2^2
157=77+80=77+10*2^3=7+10*2^0+10*2^1+10*2^2+10*2^3
So item n is
a(n)=7+10*2^0+10*2^1+10*2^2+10*2^3+…… +10*2^(n-2)
=7+10[2^0+2^1+2^2+…… +2^(n-2)]
=7+10*2*[1-2*(n-1)]/(1-2)
=7-20+20*2^(n-1)
=5*2^(n+1)-13

2 3 5 7 10 13 17 21 26 31 37 43 what are the rules?

1,2,2,3,3,4,4,5,5,6,6,
The result of subtracting the latter from the former is obvious;
Let the nth number be m; denote m (n)
M(n)=M(n-2)+n;

2 3 5 7 10 13 17 21 26 31 37 43…… What is the nth number

Square of (n-1) + 1

17 / 23 plus 1 / 4 minus 17 / 23 plus 3 / 4
1. Turn the topic into a formula
2. Out of line calculation
3. Use the simplest method

17/23+1/4-17/23+3/4
=17/23-17/23+1/4+3/4
=0+1
=1

Eight and a quarter minus (three and seventeen four plus two and a quarter)

Eight and a quarter minus (three and seventeen four plus two and a quarter)
= 33 / 4 - (4 / 3 + 9 / 4)
= 33 / 4-9 / 4-3 and 4 / 17
= 6-3 and 4 / 17
= 2 and 13 / 17

2 / 3, 8 / 5, 23 / 15, 17 / 10, 19 / 12 in descending order

General division
10/17 < 5/8 < 12/19 < 15/23 < 2/3

2 out of 3, 5 out of 8, 15 out of 23, 10 out of 17, 20 out of 29, which is bigger

20/29

Arrange 10 out of 17, 12 out of 19, 15 out of 23 and 60 out of 101 in descending order

Arrange 10 out of 17, 12 out of 19, 15 out of 23 and 60 out of 101 in descending order
10/17=60/102
12/19=60/95
15/23=60/92
10 of 17 ＜ 60 of 101 ＜ 12 of 19 ＜ 15 of 23