Logic math problems

5 problems with worked solutions.

№ 1 · Logic · Grade 1

There are 15 books on a shelf. The red book is fifth from the left. What is its position when the books are counted from the right?

№ 2 · Logic · Grade 2

Ira, Oleg, and Maxim are standing in a line. Ira is ahead of Oleg, and Oleg is ahead of Maxim. What is Oleg’s position?

№ 3 · Logic · Grade 2

A two-digit number is intended. In the tens place there is a digit 3, and the sum of its digits is 7. What number is intended?

№ 4 · Logic · Grade 3

In a two-digit number, the tens digit is 3 more than the units digit, and the sum of the digits is 11. What number is this?

№ 5 · Logic · Grade 4

The sum of three consecutive natural numbers is 72. What is the largest of these three numbers?