Find the sum of integers from 33 to 47:

33+34+...+46+47

How many zeroes are at the end of 100! = 1∙2 ∙ … ∙ 99∙100?

Tom, Michael and Jane visit the same sport club. Tom visits the club every 5th day, Michael every 6th day and Jane every 8th day. If all three of them were in the sport club on August 5th, Sunday, what will be the next day when all of them will be there?

The numeration of electrical poles starts at #1 and goes up to #212. Every fifth pole has special extra safety device. How many extra safety devices are there?

Find the biggest multiple of 36, which consists of all 10 digits, each used once.

What is triangular number 39?

How much bigger is TR(379) than TR(378)?

how many digits do you need to write all 3-digit numbers?

There were 2017 inhabitants on an island. Some of them were truth-tellers and the others were liars. The truth-tellers always tell the truth and the liars always lie. Every day, one of the inhabitants said: "After my departure the number of truth-tellers on the island will equal the number of liars" and then left the island. After 2017 days, there is nobody on the island. How many liars were there initially?

At a party there were only liars. They began to argue about how many of them there were.

The first liar said: "We are more than twelve".

The second said: "We are an even number".

The third said: "The word denoting our number consists of less than six letters". How many liars were at the party?

Write one digit on each side of 36 to make a four digit multiple of 36. How many different solutions does this problem have?

Find the 45^th triangular number.

Is the number 110111 (written in binary) even?

How many five-digit numbers are there for which each digit is either equal to both adjacent ones, or differs from its neighbors exactly by 1 (from one smaller by 1, and from the other larger by 1) and which contain the digit 5?

There are 13 students in a certain class. What is the smallest amount of students that could share a birthday in the same month?

56·328+162·44+166·44

A man wants to enclose a rectangular garden adjacent to a river. The length of the rectangle is two times the width. How many linear feet of fence must he buy if he does not need fencing along the river and the perimeter of the rectangle is 240 feet?

1245∙25∙4∙5∙2