### Number Round Up

Arrange the numbers 1 to 6 in each set of circles below. The sum of each side of the triangle should equal the number in its centre.

### Numbers as Shapes

Use cubes to continue making the numbers from 7 to 20. Are they sticks, rectangles or squares?

### How Odd

This problem challenges you to find out how many odd numbers there are between pairs of numbers. Can you find a pair of numbers that has four odds between them?

# Largest Even

##### Stage: 1 Challenge Level:

I have a pile of nine digit cards numbered $1$ to $9$.

I take one of the cards.  It is the $3$.

Which card would you choose so you could make the largest possible two-digit even number with the two cards?

We put the cards back in the pile.  This time, I choose the $6$. Which card would you choose this time to make the largest possible two-digit even number?

Have a go at this with a partner.  One of you chooses the first digit from the set of cards.  The second person then chooses a card to make the largest possible two-digit even number. You can then swap over.

Try it several times so you are sure you have a good method. Talk about your ideas with your partner so you agree together on a 'best' method.

How would your strategy change if you had to make the largest two-digit odd number?

If you don't have a partner to work with, you could use the interactivity below.  The computer selects one digit at random.   You must then choose a digit to make the largest possible two-digit even number or largest possible two-digit odd number.

Enter the biggest two-digit number you can think of that uses the digit: