The first time, a person sold $\frac{1}{4}$  the number of all apples. The second time, he sold $\frac{1}{8}$ times more before. The number of apples sold in the third time is equal to $\frac{1}{5}$ of the sum of both first time and second time. How many apples are left?  Knowing that the in the first time, he sold 5 apples more than the third times. 

Find the dividend of the following division ?

Find the greatest natural number which has different digits. Knowing that multiple of all digits is equals 288 ?

Find a 4-digit natural number. Knowing that the result for adding the number to the sum of its digits is equal 1993?

How many 4 – digit numbers which are divisible by 11 and the sum of digits is also divisible by 11 ?

The sum of four natural numbers is 2235.  If delete units digit of the first number, we get the second number. If delete units digit of the second number, we get the third number. If delete units digit of the third number, we get the four number .Find the first number.

$\frac{2}{3}$ of the sum of two numbers subtracts the difference of those two is equal to 32. If $\frac{1}{2}$ of the difference of the two numbers multiplies by 6 then the result is equal to the sum of two numbers? Find the two numbers.

A natural number with 5 digits is given. Knowing that if the number is multiplied by 4, we have a new number which can be written using the digits of first number but in the opposite order ? Find the original number.

Four numbers are given which are different than each other and 0. Find the sum of all numbers which can be written by the given four numbers, knowing that the sum of the greatest and smallest number is equal to 9889.

Natural numbers from 1 to 100 are split into 2 groups: odd numbers and even numbers. What is the difference between the sum of digits of odd number and even numbers?

How many “0” digits appear in the sequence from 0 to 99999 ?

Four consecutive natural numbers are written as thousands, hundreds, tens and units of a 4-digit number. Write the digits of that number in reverse order and we have a new 4-digit number which is greater that the original number by how many units?  

Find a natural number. Knowing that if adding that number to the sum of its digits , we have a result of 1159.

A 2-digit number is divided by the sum of its digits, giving a quotient of 4 and remainder of 3. If changing the position of the digits, the difference between the new number and the sum of its digits times 6 is equal to 5 units. Find the original number.

A natural number is written with the digits of 12345678………19981999. Find the sum of its digits.