5.4 minus 1.5 times 2.6 (calculated by a simple method)

5.4 minus 1.5 times 2.6 (calculated by a simple method)

5.4-1.5*2.6 =5.4-3.9 =1.5

1988 divided by 199 and 1999 divided by 1998, using a simple method to calculate!

1998 = 1998 + 1998 / 1999 = 1998 × (1 + 1 / 1999) = (1998 × 2000) / 19991998 divided by 1998 × [(1998 × 2000) / 1999] + 1 / 2000 = 1998 × 1999 / (1998 × 2000) + 1 / 2000 = 1999 / 200

1-1/2=1/2 2-2/5=5/8 3-3/10=10/27 7-4/17=64/17
1-1 / 2 = 1 / 2 2-2 / 5 = 5 / 8 3-3 / 10 = 10 / 27 4-4 / 17 = 64 / 17 find the fifth formula? What is the sum of the numerator and denominator of the fraction on the right side of the tenth equation?

The law of this equation is N-N / (n ^ 2 + 1) (n = 1,2,3,4.)
So the fifth equation is 5-5 / 26 = 125 / 26
The tenth equation is 10-10 / 101 = 1000 / 101, and the sum of the numerator and denominator of the fraction on the right of the tenth equation = 1000 + 101 = 1101

Please write the number in (): a.1 8 27 () b.65 37 17 ()
Please write the numbers in ():
A.1 8 27 ( )
B.65 37 17 ( )
A. 58 B.5 why?

A. 64 is more reasonable, 1 = 1 ^ 3,8 = 2 ^ 3,27 = 3 ^ 3,64 = 4 ^ 3
B.65=8^2+1,37=6^2+1,17=4^2+1,5=2^2+1

Calculation: - 7 / 27 × 34 / 37-1 + 13 / 27 × 17 / 37

=-27x37 (7x34 + 27x37 + 13x17)
=-27x37 (7x2x17 + 13x17 + 27x37)
=-27x37 (27x17 + 27x37)
=-54 out of 37

Please write the numbers in (): a.18 27 () b.65 37 17 () a.58 B.5 why?
Please write the numbers in ():
A.1 8 27 ( )
B.65 37 17 ( )
A. 58 B.5 why?

A should be 64, the third power of 1, 2, 3 and 4
B is 5, because the difference between 65 and 37 is 28, the difference between 37 and 17 is 20, and the difference between 17 and 5 is 12
The three terms form an arithmetic sequence

Is there any simple algorithm for 714285 / 37 / 27 * 17 * 7 (where / is division sign and * is multiplication sign)?
Without brackets, divide and multiply in order

The title is not clear
The addition of parentheses
714285=142857*5
142857*7=999999
999999*5*17/(37*27)
=999999*5*17/(37*3*9)=999999*5*17/(111*9)=1001*85=85085

Simple calculation of 17 + 22 + 27 + 32 + 37 + (add to the 100th number)

The first number is 12 + 5 * 1, the second is 12 + 5 * 2, and the 100th is 12 + 5 * 100
Calculation of the original problem = 12 * 100 + 5 * (1 + 2 +... + 100) = 1200 + 5 * 5050 = 26450

There are 15 prime numbers within 50: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47,
Please select 10 and fill in the small circle in the figure above, so that the difference between the two prime numbers is equal to a composite number within 10
○-○ ○-○
╲╲ ╱╱
○ - ○ = ○
╱╱ ╲╲
○-○ ○-○

In the middle is four,
3,7 ,13,17,19,23 ,37,41 ,43,47
There are other options, you can try to write it yourself

The product of 37 × () is a prime number 2, which can be 1, or other numbers 3, which can be prime numbers

1 is the correct answer
If it is not 1, then the product has at least two factors, 37 and the number in brackets. According to the definition, besides 1 and itself, there are also factors, that is, sum numbers
So it can only be 1 in brackets