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?

NRICH: Quadratic Patterns
NRICH (University of Cambridge)

Surprising numerical patterns can be explained using algebra and diagrams…

NRICH: Think of Two Numbers
NRICH (University of Cambridge)

Think of two whole numbers under 10, and follow the steps. I can work out both your numbers very quickly. How?

NRICH: The Number Jumbler
NRICH (University of Cambridge)

The Number Jumbler can always work out your chosen symbol. Can you work out how?

NRICH: Adding in Pairs
NRICH (University of Cambridge)

These are the results when 3 numbers were added in pairs. What were the numbers?

NRICH: Sum and Differences
NRICH (University of Cambridge)

Three numbers add up to 100. The difference between the larger two is 12 and the difference between the smaller two is 2. What are the numbers?

NRICH: The Simple Life
NRICH (University of Cambridge)

The answer is 5x+8y… What was the question?

NRICH: Adding and Multiplying
NRICH (University of Cambridge)

Amy misread a question and got an incorrect answer. What should the answer have be?

NRICH: Multiplication Square
NRICH (University of Cambridge)

Pick a square within a multiplication square and add the numbers on each diagonal. What do you notice?