NRICH: More Number Pyramids
NRICH (University of Cambridge)

In the number pyramid below, the number in the bottom left hand corner determines all the other numbers.

NRICH: Number Pyramids
NRICH (University of Cambridge)

In a number pyramid, the numbers on the lower layers determine the numbers above them.

NRICH: Special Numbers
NRICH (University of Cambridge)

One day our teacher asked us a puzzling question.

NRICH (University of Cambridge)

Think of a number and follow the machine’s instructions… I know what your number is! Can you explain how I know?

NRICH: Reversals
NRICH (University of Cambridge)

Where should you start, if you want to finish back where you started?

NRICH: Perimeter Expressions
NRICH (University of Cambridge)

Create some shapes by combining two or more rectangles. What can you say about the areas and perimeters of the shapes you can make?

NRICH: Always a Multiple?
NRICH (University of Cambridge)

Think of a two digit number, reverse the digits, and add the numbers together. Something special happens…

NRICH: Crossed Ends
NRICH (University of Cambridge)

Crosses can be drawn on number grids of various sizes. What do you notice when you add opposite ends?

NRICH: Black and Gold Storeys
NRICH (University of Cambridge)

25 of the storeys of a 50 storey building are painted gold, and the rest are painted black…

NRICH: 8 in a Row
NRICH (University of Cambridge)

The sum of five consecutive integers is equal to the sum of the next three consecutive integers. Can you find the largest of these integers?

NRICH: Grow up Fast
NRICH (University of Cambridge)

How old will Julie be when her age is equal to the sum of her daughters’ ages?