Which of these fruits are *not* berries: strawberry, blackberry, banana, tomato, and blueberry? Turns out just two of them aren’t: the strawberry and the blackberry. As it turns out, a berry is any fruit that grows from one flower and has just one “ovary” to hold seeds. In the case of a strawberry, it has lots of ovaries and each one holds one seed — those yellow dots all around the outside. Meanwhile, tomatoes, avocados, bananas and pumpkins *are* berries. We hardly think of tomatoes or pumpkins as being fruits at all, much less berries, but they grow from flowers according to the rules. Blackberries and raspberries mix things up even more: each of them is an “aggregation” (cluster or clump) of “drupelets,” the name for each little juicy ball, each of which holds one seed. So as berry season winds down, don’t be sad — if you’re missing berries, just nibble on some bananas and tomatoes.

*Wee ones:* If you nibble on a blackberry, a tomato, a banana and a blueberry, how many real berries are you nibbling?

*Little kids:* A strawberry has about 200 seeds on the outside! If you bite off 1/2 of them, how many seeds are left? *Bonus:* How many seeds are on 10 strawberries?

*Big kids:* If you eat a raspberry that has 37 drupelets and a blackberry with 54 drupelets, how many more drupelets does the blackberry have? *Bonus:* If you eat 10 of each, how many juicy drupelets do they have altogether?

*The sky’s the limit:* If you have a handful of raspberries, each with 36 drupelets, and strawberries each with 200 seeds, and the number of strawberries is 1/5 the number of raspberries and there are 80 more seeds than drupelets, how many of each do you have?

Answers:

*Wee ones:* 3 real berries.

*Little kids:* 100 seeds. *Bonus:* 2,000 seeds.

*Big kids:* 17 more drupelets. *Bonus:* 910 drupelets.

*The sky’s the limit:* You have 4 strawberries and 20 raspberries. To solve with algebra, if there are s strawberries and r raspberries:

5s = r (relation between number of each)

200s = 36r + 80

Substituting 5s for r, we get

200s = 36 (5s) + 80

200s = 180s + 80

20s = 80

s = 4

That gives us 4 strawberries and 5 times that many raspberries (20). To check, the 20 raspberries will have 720 drupelets, and the strawberries will have 800 seeds, which is 80 more.

Laura Bilodeau Overdeck is founder and president of Bedtime Math Foundation. Her goal is to make math as playful for kids as it was for her when she was a child. Her mom had Laura baking before she could walk, and her dad had her using power tools at a very unsafe age, measuring lengths, widths and angles in the process. Armed with this early love of numbers, Laura went on to get a BA in astrophysics from Princeton University, and an MBA from the Wharton School of Business; she continues to star-gaze today. Laura’s other interests include her three lively children, chocolate, extreme vehicles, and Lego Mindstorms.