Scientific counting approximate significant number What's the exact decile of 0.00000007? How many significant numbers are there

Scientific counting approximate significant number What's the exact decile of 0.00000007? How many significant numbers are there

To be precise to the tenth is like this: 12345 becomes the fourth power of 1.2 * 10
So your question should be 0.7 * 10 seventh power, the number of significant digits is naturally 2, because 07 is two digits

A + 2B = 0 a ^ 3 + 2Ab (a + b) + 4B ^ 3-8 (^ is a power)

A ^ 2-2ab + 2B ^ 2-4b + 4 = 0 to the - B power of (a-5)
A ^ 2 is the square of A

a^2-2ab+2b^2-4b+4=0
(a-b)^2+(b-2)^2=0
a=b,b=2
So, a = b = 2
The - B power of (a-5)
=(2-5)^(-2)
=(-3)^(-2)
=1/9

From the table, you can find out what is the rule of the number of single digits of power n of 2? What is the number of single digits of power 2005 of 2

The single digits of the n-th power of 2 are 2,4,8,6,2... Cycles
The remainder of 2005 / 4 = 1
So, the single digit of 2 in 2005 is 2

Under what circumstances can Newton Leibniz formula not be used for definite integral of higher numbers?
Why can't we use that formula

Operation of power
2X + 1 power of 2 + x power of 4 = 48
The X + 1 power of 3, the x power of 2 minus the x power of 3, the X + 1 power of 2 = the square of 2, the square of 3
Find X in the above formulas

2X + 1 power of 2 + x power of 4 = 48
2^(2x+1)+4^x=48,
2*2^2x+4^x=48,
2*4^x+4^x=48,
3*4^x=48,
4^x=16,
x=2,
The X + 1 power of 3, the x power of 2 minus the x power of 3, the X + 1 power of 2 = the square of 2, the square of 3
3^(x+1)*2^x-3^x*2^(x+1)=2^2*3^2
3*3^x*2^x-2*3^x*2^x=36,
3^x*2^x=36,
6^x=36,
x=2

The operation of power,
If 2 ^ m = x, then 4 ^ m=
If x = 2 ^ m + 1, 3 + 4 ^ m, then y is expressed by the formula containing X
Compare size
3^555
4^444
5^333

12 if 2 ^ m = x, then 4 ^ m = x ^ 2
2.X = 2^m +1 2^m = x-1
y=3+4^m = 3+ (2^m)^2 = 3+(x-1)^2 = X^2 - 2x + 4
Y = X^2 - 2 x + 4
3.3^555=(3^5)^111
4^444=(4^4)^111
5^333=(5^3)^111
∵3^5=243,4^4=256,5^3=125
∴(5^3)^111＜(3^5)^111＜(4^4)^111
∴5^333＜3^555＜4^444

On the operation of power
10=2x5,10=(2x5)²
100=4x5=2²x5²,100=10²=（2x5）²
1000=8x125=2³x5³,1000=10³=（2x5）³
……
What rules do you find in it?

Exponents are constant, bases are multiplied

The sum of 27 continuous natural numbers is 1998, and the smallest one is 1998______ ．

According to the meaning of the question: the middle number is: 1998 △ 27 = 74, that is, the fourteenth number is 74, because the fourteenth number is 14-1 = 13 larger than the smallest number, so the minimum natural number is: 74-13 = 61

If the sum of three continuous natural numbers is 27, then the sum of squares of these three numbers is 27______ ．

27 △ 3 = 9; 9-1 = 8; 9 + 1 = 10; 82 + 92 + 102, = 64 + 81 + 100, = 245; so the answer is: 245