The total weight of several stones is 707 kilograms. The lightest five stones weigh 180 kilograms. The heaviest six stones weigh 234 kilograms. The weights of stones are distinct and are not necessarily whole numbers. What is the number of stones ?

A and B are sibling but of different genders. A has an even number of brothers and an even number of sister ( Zero does not count )/ B has an odd number of brothers and an odd number of sisters. What is the minimum number of children in this family ?

Mr. Trump buys 71 pencils. Each pencil costs 2 dollars, and 67 pens, each pen costs 3 dollars. He gets a discount of 1 dollar for 3 pencils he buys and a discount of 2 dollars for 5 pens he buys. How much in total does he pay? 

Cho các số đo thời gian : 2 giờ 50 phút ; 2 giờ 5 phút ; 3 giờ 27 phút; 3 giờ.

Viết các số đo thời gian trên theo thứ tự từ bé đến lớn :

The perimeter of the parallelogram ABCD is 48m. The height corresponding to the base CD is 7m and the side AD is 9m. Find the area of the parallelogram ?

The quotient of two numbers is one fifth of the bigger number and four times the smaller one. What is the quotient?

Jack is ranked 7th in his class from top and 21st from bottom. How many students are there in Jack’s class?

James has 2 more chickens than dogs. One half the chicken legs are equal to three eighths the dog legs. How many legs are there in total?

The average of 17 distinct whole numbers is 17.What is the largest possible value of these numbers?

Thirteen friends join a sport club together. Eight of them play football, six of them play tennis and five of them play badminton. If everyone plays sport but no one plays only two kinds of sport, how many people play all three kinds?

Alice said to her mother, “If I reverse the two digits of my age, I will get your age”. Her mother said, “Tomorrow is my birthday, and my age will then be three times yours”. It is known that their birthdays are not on the same day. How old is Alice?

Forty students from five grades brought 50 candies for the “Trick or Treat” game in a Halloween party. It is known that students from the same grade brought an equal number of candies, while students from different grades brought different numbers of candies. How many students brought exactly one candy? 

Two of my digits are odd, but my units digit is even. The sum of my digits is 14. I’m between 567 and 599 and I' m not 590. What number am I? 

Find the sum of all 2 – digit numbers such that each number is 13 times its tens digit ?

A boy weighed his twin cat and two identical hat together and got 2200g. He then weighed one hat and a 10kg -  weight and got 10450g. What was the weght of one cat ?