Being collaborative

On my calculator I divided one whole number by another whole number and got the answer 3.125. If the numbers are both under 50, what are they?

Peter wanted to make two pies for a party. His mother had a recipe for him to use. However, she always made 80 pies at a time. Did Peter have enough ingredients to make two pumpkin pies?

Can you draw a square in which the perimeter is numerically equal to the area?

Arrange cards numbered 1 to 20 into 6 piles. Can each pile add to the same total?

Can you fill in this table square? The numbers 2-12 were used to generate it with just one number used twice.

One quarter of these coins are heads but when I turn over two coins, one third are heads. How many coins are there?

The discs for this game are kept in a flat square box with a square hole for each. Use the information to find out how many discs of each colour there are in the box.

This multiplication uses each of the digits 0 - 9. Can you work out where each digit goes?

Can you use four digits to make four two-digit numbers that add to 100?

Can you make square numbers by adding two prime numbers together?