Calculate quickly:

$10-\frac{1}{2}-\frac{5}{6}-\frac{11}{12}-\frac{19}{20}-.....-\frac{89}{90}$

Find x and y such that $\overline{x2012y}$ divided by 2; 3; 5; 9 then we obtain a remainder by 1 ?

Ha is 9 flowers more than An. Such that $\frac{1}{7}$the number of flowers of Ha is equal to 1/4 the number of flowers of An. How many flowers does each person have ?

Calculate the sum:

$1+\frac{1}{3}+\frac{1}{9}+\frac{1}{27}+\frac{1}{81}+\frac{1}{243}+\frac{1}{729}$

( Write the result as a/b ) 

Calculate quickly : $A=\frac{2004\times 37+2004+2\times 2004+2004\times 59+2004}{324\times 321-201\times 324-324\times 101-18\times 324}$

( Write the result as a/b )

There are 45 workers to do a job together.They will complete the job in 10 days. After doing in 4 days together, 15 workers is transfered to do other job. How many days do the others workers continue to complete the job ?

Find two digits a and b such that : $\frac{1}{3}=\frac{1}{a}+\frac{1}{b}$

There are three class : 4A ; 4B ; 4C , they plant tree. The number trees of 4A and 4B is 41. The number trees of 4B and 4C is 43.The number trees of 4C and 4A is 42. How many trees does each class plant ?

The average of the first number and the second number is 39 . The average of the second number and the third number is 30. The average of the first number and the third number is 36. Find three numbers ?

The perimeter of a rectangle is 784m. Such that if writing digit 2 into before the width, it will be the length. Find the area of the rectangle ?

Calculate quickly : A = $\frac{1}{2}+\frac{5}{6}+\frac{11}{12}+\frac{19}{20}+\frac{29}{30}+\frac{41}{42}+\frac{55}{56}+\frac{71}{72}+\frac{89}{90}$

( Write the result as a/b )

Given the expression: S = $\frac{1}{11}+\frac{1}{12}+\frac{1}{13}+\frac{1}{14}+\frac{1}{15}+...+\frac{1}{20}$

Compare S and $\frac{1}{2}$? ( Fill the suitable sign : > ; < ; = )

Given the fraction : M = $\frac{1+2+...+9}{11+12+...+19}$ . To the value of the fraction is no change, What are numbers deleted in the numerator and the denominator ?

A is 2004 – digit natural number. A divide by 9 ; B is the sum of all digits of A; C is the sum of all digits of B ; D is the sum of all digits of C. Find D ?

Find the natural number such that take $\frac{1}{3}$ of that number divides by $\frac{1}{17}$ of that number, the remainder is 100 ? )