15 = 7 + 8 and 10 = 1 + 2 + 3 + 4. Can you say which numbers can be expressed as the sum of two or more consecutive integers?
How many moves does it take to swap over some red and blue frogs? Do you have a method?
Time for a little mathemagic! Choose any five cards from a pack and show four of them to your partner. How can they work out the fifth?