A Cool 100 Grand…Kids

Here's your nightly math! Just 5 quick minutes of number fun for kids and parents at home. Read a cool fun fact, followed by math riddles at different levels so everyone can jump in. Your kids will love you for it.

A Cool 100 Grand…Kids

June 16, 2015

When parents have children who grow up to have their own children, those new kids are grandchildren to the parents who started it all. And if you have 12 kids of your own who have kids, you can end up with a lot of grandkids — who, if they have kids, will give you lots of great-grandchildren. Leo and Ruth Zanger have perfect numbers on this: their 12 kids have had 53 kids in total (their grandkids), and so far those 53 grandchildren have given them 46 great-grandchildren, one of whom just had a child who counts as a great-great-grandchild…so now Leo and Ruth have 100 descendants in total! The first grandchild was born in 1975, before they’d even finished having their own 12 kids (the youngest had 10 nieces and nephews already when he was born). Now when the family gets together, they need either 50 pounds of ham or 10 turkeys to feed everyone — and name tags would help, too.

Wee ones: If you buy 8 turkeys for the holiday party and find you need 1 more, what number turkey is next?

Little kids: If Leo and Ruth have 53 grandkids and 46 great-grandkids, do they have more grandkids or great-grandkids?  Bonus: How many more?

Big kids: If you have 3 kids who each have 3 kids who each have 3 kids themselves…how many great-grandchildren do you have?  Bonus: If each of your great-grandkid eats 2 burgers at the family picnic, will 50 burgers be enough?

The sky’s the limit: If you have 2 kids who each have 2 kids who each have 2, and so on, how many generations will it take to give you 30 descendants in total? (The first 2 kids count as the first generation.)



Wee ones: 9 turkeys.

Little kids: More grandkids.  Bonus: 7 more.

Big kids: 27 great-grandchildren.  Bonus: No, because you’ll need 54!

The sky’s the limit: It will take 4 generations, since that will give you 2 kids, 4 grandkids, 8 great-grandchildren, and 16 great-great-grandchildren. The easiest way to solve this is just to add the next power of 2 until the total comes to 30.

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About the Author

Laura Overdeck

Laura Overdeck

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.

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