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How many zeros are there after the factorial of 1991?
The key is to find out the number that can produce 0. We can know that the multiple of 5 and the multiple of 2 will produce 0. And the multiple of 2 is more than the multiple of 5, so we only need to find out how many times of 5. 1991 △ 5 ^ 1 = 1991 △ 5 = 398.2, there are 398 5 ^ 1; 1991 △ 5 ^ 2 = 1991 △ 25 = 79.64, there are 79 5 ^ 2; 1991 ÷ 5 ^ 3 = 1991 ￣ 125 = 15.928, there are 15 5 ^ 3; 1991 ￣ 5 ^ 4 = 1991 ￣ 625 = 3.1856, There are three 5 ^ 4. The sum of them is 398 + 79 + 15 + 3 = 495. That is to say, in the multiplication formula from 1 to 1991, there are 495 prime factors of 5 that can be decomposed. When each 5 is multiplied by an even number, it will produce a 0. Therefore, there are 495 zeros
For rational numbers a and B, define the operation a ★ B = a + B / AB, and calculate: (- 1) ★ (2 ★ 1)
Original formula = - 1 * (2 + 1 / 2 * 1)
=-1*（3/2）
=-1+3/2/（-3/2）
=-1/3
Please summarize your problem here. It is known that XY is a rational number. If a new operation is specified, define x * y = XY-2 It is known that: XY is a rational number. If a new operation is specified, X * y = XY-2 is defined. According to the meaning of the operation symbol, complete the following questions: 1, find 3 ＊ M = 13, find the value of M
3@m=3 *m-2=13
3m=15
M=5
If the meaning of "*" is a * b = AB / A + B, find the value of 2 * 3?
2*3
=2×3/2+3
=6/5
We now stipulate that the operation symbol "(XX); means a () B = a times B than a plus B, then the value of 10 () (10 () 10) is () yyyyy What is the value
10()10=100/20=5
10(10()10)=10*5/(10+5)=10/3
So the answer is 10 / 3
*A * b = A-B / AB is defined and the value of 2 * [3 * (- 2)] is calculated Right now,
3*(-2)=[3-(-2)]/-6= -5/6
2*(-5/6)=[2-(-5/6)]/(-5/3)=-1.7
If the meaning of symbol * is a * b = A.B / A + B, find 2 * (- 3) * 4
The meaning of "*" has no influence on the solution of the problem. You can calculate a * b = AB / A + B and find 2 * (- 3) * 4 by substituting the number into the formula
=[2 times (- 3) / (2-3)] * 4
=6*4
=6 times 4 / (6 + 4)
=2.4
a*b=ab/a+b
A * b = 2 * (- 3) = [2 times (- 3) / (2-3)] = 6
A * b = 6 * 4 = 6 times 4 / (6 + 4) = 2.4
What are the rules of addition, subtraction, multiplication, division and power?
The addition rule of rational number is: 1. Add the same sign, take the same sign, and add the absolute value. 2. If the absolute value is unequal, take the adder sign with larger absolute value and subtract the smaller absolute value with the larger absolute value
What is the law of operation of multiplication
The law of operation of multiplication has the property of commutation, which is also called multiplication
The commutative law of multiplication is called commutative law when two numbers are multiplied and the position of commutative factors is invariant. If a × B = B × a, it is called commutative law
Combining law, when three numbers are multiplied, the first two numbers are multiplied, then another number is multiplied, or the last two numbers are multiplied first and then another number, and the product remains unchanged
The main formula is a × B × C = a × (B × C),
The distribution rate, the multiplication of two numbers by the same number is equal to multiplying two adders with this number respectively, and then adding up the two products, and the sum remains unchanged
The letter expression is: a × (B + C) = a × B + a × C
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The problem of rational multiplication It is known that the third power of a = - 1 (1) Find 1 + A + A's 2nd power + A's 3rd power + A's 4th power +... " +The value of a to the power of 2010 (2) Let a multiply a to the second power of a times the third power of a times the fourth power of A Multiply a to the power of 2010 How thick is a piece of paper with a thickness of 0.2mm after folding it in half for 10 times?
It is the first power of a = - 1 power of a = - 1 power of a = - 1 power of a = - 1 power of a = - 1 power of a = - 1 power of a = - 1 power of a = - 1-1 of power of it +A's 2010 power = 1. The thickness of 0. 2mm paper stack once
RELATED INFORMATIONS
- 1. The operation procedure of the new operation symbol * is defined as a * b = 1 3a−1 4b, then (1) Find 5 * (- 5); (2) Solve the equation 2 * (2 * x) = 1 * X
- 2. + 3! + - 5! + - 4! + - 1! + - 2
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