Starting out: You bid more, since 5 is more than 4, so you'll get to buy them!
Challenge 1: $2 more
Challenge 2: $13
Challenge 3: 23 pairs, since they'd have 24 if they had 2 of each
Challenge 4: $27.98
Experts: 20 different combinations. For each of the 5 colours you wear, there are 4 remaining colours from which your dog can choose. If you wear red, your dog can wear yellow, or blue, or green, or black, making 4 combos. If you instead wear yellow, then your dog could wear red, blue, green, or black, adding another 4...and so on. By the time you try all 5 colours, you've created 5 sets of 4 combos, making 20 total.
Spring is here, and that means our friends the flowers are just around the corner. What's cool is that some flowers do math without even knowing it! Sunflowers always have a certain numbers of petals -- only some numbers can work. There's a special set of numbers where you get each number by adding the 2 numbers before it. You start with 1 and 1, which gives you 2...then 2+1 is 3...then 3 plus that 2 gives you 5...5 plus that 3 gives 8, and so on. They're called the Fibonacci numbers, and sunflowers always have a Fibonacci number of petals! Let's see how big that flower can get.
Starting Out: If the first few Fibonacci numbers are 1, 2, 3 and 5, which number did we skip that we would have said if counting?
Challenge 1: If the last 2 Fibonacci numbers we got were 5 and 8, what's the next number? (Reminder: You get each number by adding the previous two numbers.)
Challenge 2: If you have a flower with that many petals and another with 5 petals, how many do they have together?
Challenge 3: Can a sunflower have 25 petals?
Challenge 4: For fun we also have "Tribonacci" numbers, where you add the last 3 numbers to get the next. Since it also starts with 1, 1, and 2, what are the next 3 Tribonacci numbers? See if you can remember all the pieces in your head!