
MathematicalPuzzles.com
Brain teasers with 9 numbers 

Number puzzles as mental jogging from 10 years upwards
Brain teasers in various levels of difficulty ("easy", "medium", "hard" and "very hard") will keep your grey cells active. Nine singledigit numbers are linked using the basic arithmetical skills, setting you challenges in terms of mental arithmetic, concentration, logic and retention of data. A varying quantity of numbers in different patterns are provided in advance to help you, with the amount of help depending on the level of difficulty selected. And even for experienced math 'experts' and problem solvers there are some hard nuts to crack – you'll be surprised at the number of possible combinations there are. Ten minutes spent every day in mental jogging will make a noticeable difference to your intellectual fitness.
Rules: 
You enter a number from 1 to 9 in the squares, but numbers can only be used once. The rule about multiplication/division ahead of addition/subtraction doesn't apply!

In order to ensure that clear answers are always produced it is not advisable to modify the math problems, which were designed with a special software program.

