1: the perimeter of a circle is 15,7 dm. Its's area is...cm2

2: the ratio of the number of girls to the number of boys in a classroom is 5:4. When 10 girls left the classroom, the ratio of the number of boys to the number of girls became 4:3. How many students were in the classroom at first?

3: 47/250 dm3=...cm3

4: At the party 60% of the boys are dancing with 80% of the girls. How many people are dancing if there are 35 people ( A pair cludes only one boy and one girl)

5: An aquarium is 8dm deep, 12 dm long and 0,3 m wide. What is the volume of the aquarium in cubic centimeter?. Answer: the volume of the aquarium is...cm3

1/ Write the equivalent to fraction 3/5 with a denominator of 100.Result is 3/500 , 30/500 , 300/5 , 60/100 

2/ If the sum of two numbers is the greatest-four digits number and the ratio of these numbers is the smallest -two digits number . 999 and 989 , 900 and 99 , 909 and 9090 , 989 and 10 

3/ 7 hamburgers and 5 ice creams cost $32.10 hamburgers and 5 ice creams cost $35. The cost of one hamburger is $ .... 

4/ John has sixteen balls . Jack has one quarter as ball as John . Jack has ....... balls 

5/ Charlie has eighteen pens more than bill . 

Bill has one third as pen as Charlie . Bill has : 6 pens , 9 pens , 2 pens , 3 pens 

Câu 1 :Each of cars can take 8 people. How many cars needed to take 124 people?

Câu 2 : How many integer numbers between 200 and 300 are there for which the hundreds digit equals the sum of the other two digits?

Câu 3 : The average of five numbers is 20. The average of the five number is 18 when one of the numbers is chaned to 4. What is the orginal value of the changed number?

Câu 4 :A book has 250 pages starting at number 1. How many digits are there in the page numbers of the book?

Câu 5 : Find A, if A is 3 less than the average of 48; 55; 29 and A. The value of A is…

Câu 6 : The sum of denominator and numerator of a fraction is 121 and the fraction is equal to 4/7. Find the denominator of the fraction?

Câu 7 : The sum of two numbers is equal to 77. If the first number is multiplied by 8 and the second by 6, the two product are equal. The larger of these numbers is…

Câu 8 : Which is the greatest 2 - digit number divisible by 2, 3 and 4?

Câu 9 : Calculate: (1 + 2/5) x 6/7.

Câu 10 : Give the number sequence: 1, 4, 7, 10, 13, … Find the 15th term of the number sequence.

1) ABC is a triangle where M is the midpoint of segment BC.

MD and ME are two bisectors of triangles AMB and AMC respectively.

If AM= m; BC = a . Then DE = ???

2)\(\dfrac{1}{\left(x+29\right)^2}+\dfrac{1}{\left(x+30\right)^2}=\dfrac{5}{4}\)

What is the product of all real solutions to the equation above?

3) The sum of all possible natural numbers n such that

\(n^2+n+1589\) is a perfect square is.....

4) Given that x is a positive integer such that x and x+99 are perfect squares

The sum of integer x is ...

5)The operation @ on two numbers produces a number equal to their sum minus 2. The value of

(...((1@2)@3....@2017)

6) Given f(x)=\(\dfrac{x^2}{2x-2x^2-1}\)

=> \(f\left(\dfrac{1}{2016}\right)+f\left(\dfrac{2}{2016}\right)+f\left(\dfrac{3}{2016}\right)+...+f\left(\dfrac{2016}{2016}\right)\)

Các bn giúp mk vs >>> tks nha!!!

Fill in the blank with the suitable number
Question 1:
Fill missing number in the blank
41165+23042=23042+
Question 2:
Fill missing number in the blank
54723+
=27849+54723
Question 3:
Calculate: 4159+2615+421=
Question 4:
The sum of two numbers is 98 and their difference is 24. The greater number is 
Question 5:
If a square has one side’s length is 12cm then its perimeter is 
cm
Question 6:
Find the value of 2356+a-b for a=1482, b=3105
Answer: 
Question 7:
Think of a number that if you add 720 to it the answer will be 1427. The number is 
Question 8:
If the perimeter of a square is 104m then its one side’s length is 
m
Question 9:
I am an even 2-digit number. The sum of my tens digit and my ones digit is 11 and their difference is 5. Who am I?
Answer: 
Question 10:
The perimeter of a rectangle is 72cm and its length is 12cm more than its width. Its length is 
cm