An investigation involving adding and subtracting sets of consecutive numbers. Lots to find out, lots to explore.

Roll two red dice and a green dice. Add the two numbers on the red dice and take away the number on the green. What are all the different possible answers?

Can you go through this maze so that the numbers you pass add to exactly 100?

Use the 'double-3 down' dominoes to make a square so that each side has eight dots.

Use these four dominoes to make a square that has the same number of dots on each side.

Lolla bought a balloon at the circus. She gave the clown six coins to pay for it. What could Lolla have paid for the balloon?

Amy has a box containing domino pieces but she does not think it is a complete set. Which of her domino pieces are missing?

Katie had a pack of 20 cards numbered from 1 to 20. She arranged the cards into 6 unequal piles where each pile added to the same total. What was the total and how could this be done?

The value of the circle changes in each of the following problems. Can you discover its value in each problem?

Choose four different digits from 1-9 and put one in each box so that the resulting four two-digit numbers add to a total of 100.

Ten cards are put into five envelopes so that there are two cards in each envelope. The sum of the numbers inside it is written on each envelope. What numbers could be inside the envelopes?

A game for two people, or play online. Given a target number, say 23, and a range of numbers to choose from, say 1-4, players take it in turns to add to the running total to hit their target.

Four bags contain a large number of 1s, 3s, 5s and 7s. Pick any ten numbers from the bags above so that their total is 37.

There is a clock-face where the numbers have become all mixed up. Can you find out where all the numbers have got to from these ten statements?

Tim had nine cards each with a different number from 1 to 9 on it. How could he have put them into three piles so that the total in each pile was 15?

This challenge is a game for two players. Choose two of the numbers to multiply or divide, then mark your answer on the number line. Can you get four in a row?

Use your addition and subtraction skills, combined with some strategic thinking, to beat your partner at this game.

This challenge combines addition, multiplication, perseverance and even proof.

This task combines spatial awareness with addition and multiplication.

Explore Alex's number plumber. What questions would you like to ask? Don't forget to keep visiting NRICH projects site for the latest developments and questions.

You are organising a school trip and you need to write a letter to parents to let them know about the day. Use the cards to gather all the information you need.

Can you use the information to find out which cards I have used?

Look at three 'next door neighbours' amongst the counting numbers. Add them together. What do you notice?

Explore Alex's number plumber. What questions would you like to ask? What do you think is happening to the numbers?

How could you arrange at least two dice in a stack so that the total of the visible spots is 18?

This dice train has been made using specific rules. How many different trains can you make?

In this game for two players, the idea is to take it in turns to choose 1, 3, 5 or 7. The winner is the first to make the total 37.

Can you find all the ways to get 15 at the top of this triangle of numbers? Many opportunities to work in different ways.

Try out some calculations. Are you surprised by the results?

Are these statements always true, sometimes true or never true?