Place the same number in all blanks ___ so that the following would be correct:

___ + ___ + ___ + ___ = 2 × 100. What is this number?

How many odd numbers are there from 40 to 52?

How many times is the number 1000 – 8 × 100 greater than 116 – 16 × 7?

What digit should we replace * with? 3 × 4 × 8 = 6 × 2 × ∗

Find x if 4 + 2x is a number between 1 and 9, and 4 × + 2 is a number

between 9 and 19.

Which of the symbols “<” , “>” or “=” should we replace ● with?

12 ÷ 6 × 2 ● 12 ÷ (6 ×2)

How many digits are used to write down the even numbers from 7 to 17?

How many minutes should we subtract from 240 seconds in order to get 1

minute?

How many of the symbols “+” must be swapped with the symbol " × ", so that

the equation below would be correct?

0 + 2 + 2 + 5 + 5 = 100

Each two neighbouring digits of a number form two-digit numbers in the

same order, which are divisible either by 15, or by 23. How many digits at

most could this number have?

Hint: In the number 9534, the neighbouring digits (form the numbers 95, 53,

34 (in the same order).

In 10 years, Claire will be three times her current age. In how many years will

she be 18 years old?

The number A is the greatest three-digit number with 18 as the sum of its

digits. The number B is the smallest three-digit number with 18 as the sum of

its digits. By how much is the number А greater than the number В?

Calculate □ - ☺ + ⚪, if 4 a number smaller than 16.

Which digit should we replace * with, so that the equation would be correct?

15 × ∗ + 70 = 1 ∗ 0

Find the possible perimeter of a rectangle if the length of one of its sides is 4

cm and the difference of the lengths of two of its neighboring sides is 2 cm.

The perimeter of a rectangle is 22 cm. A square has been drawn externally on

the each of the sides of the rectangle. This has resulted in a new figure. Find

the perimeter of the new figure in cm.

There are 5 green and 6 yellow points on a plane. I connected each two of

them with a line segment. How many of these line segments have endpoints of

the same colour?

I wrote down four numbers. Some of them are even, and some are odd. None

of the even numbers is written before or after another even number. None of

the odd numbers is between 2 even numbers. How many even numbers could

there be?

There are some shoes in a dark storage room – 5 pairs of black shoes and 6

pairs of brown shoes. At least how many shoes would you need to take

(without being able to see) in order to make sure that you would have taken at

least 2 pairs of shoes of different colors? (Keep in mind that since the room is

dark, you would not be able to tell the difference between the colors of the

shoes and whether each shoe is left or right.)