Exploring and noticing

There are 319 NRICH Mathematical resources connected to Exploring and noticing
Hundred Square
problem

Hundred Square

Age
5 to 11
Challenge level
filled star filled star empty star
A hundred square has been printed on both sides of a piece of paper. What is on the back of 100? 58? 23? 19?
The Tall Tower
problem

The Tall Tower

Age
5 to 7
Challenge level
filled star filled star filled star
As you come down the ladders of the Tall Tower you collect useful spells. Which way should you go to collect the most spells?
A Numbered Route
problem

A Numbered Route

Age
7 to 11
Challenge level
filled star filled star empty star
Can you draw a continuous line through 16 numbers on this grid so that the total of the numbers you pass through is as high as possible?
Tilted Squares
problem

Tilted Squares

Age
11 to 14
Challenge level
filled star empty star empty star
It's easy to work out the areas of most squares that we meet, but what if they were tilted?
Your number is...
problem

Your number is...

Age
7 to 14
Challenge level
filled star empty star empty star
Think of a number and follow the machine's instructions... I know what your number is! Can you explain how I know?
Number Tracks
problem

Number Tracks

Age
7 to 11
Challenge level
filled star empty star empty star
Ben's class were cutting up number tracks. First they cut them into twos and added up the numbers on each piece. What patterns could they see?
Pair Products
problem

Pair Products

Age
14 to 16
Challenge level
filled star empty star empty star
Choose four consecutive whole numbers. Multiply the first and last numbers together. Multiply the middle pair together. What do you notice?
Special Numbers
problem

Special Numbers

Age
11 to 14
Challenge level
filled star empty star empty star
My two digit number is special because adding the sum of its digits to the product of its digits gives me my original number. What could my number be?
Farey Sequences
problem

Farey Sequences

Age
11 to 14
Challenge level
filled star filled star empty star
There are lots of ideas to explore in these sequences of ordered fractions.
Polite Numbers
problem

Polite Numbers

Age
16 to 18
Challenge level
filled star filled star empty star
A polite number can be written as the sum of two or more consecutive positive integers, for example 8+9+10=27 is a polite number. Can you find some more polite, and impolite, numbers?