Do you know any twins? Twins are siblings born on the same day! Sometimes twins are “identical”, which means they look exactly alike. About 3 in 100 kids are twins, and 1 in 100 are identical twins. But even more rare are triplets, when three kids share the same parents and birthday. Triplets are 1 in 1,000! And then there are quadruplets – 1 in 8,000 – and quintuplets – 1 in 20,000 kids. The real math question is, when do we need to get a second cake?
Wee ones: Which are there more of: days that are your birthday, or days that aren’t your birthday?
Little kids: If your neighborhood celebrates a pair of twins’ birthdays on Tuesday, a set of triplets’ birthdays on Wednesday, and your own birthday on Thursday, how many kids celebrate birthdays that week? Bonus: If a group of quintuplets – 5 siblings – is running around and all but 1 of them are wearing sneakers, how many sneakers is the group wearing?
Big kids: Which party has more kids: 5 pairs of twins, or 4 sets of triplets? Bonus: How many pairs of twins would it take to equal 30 sets of triplets?
Answers:
Wee ones: Days that aren’t your birthday – that’s why it’s special!
Little kids: 6 birthdays: 2 + 3 + 1. Bonus: 8 sneakers: 4 kids with 2 sneakers each.
Big kids: The triplets: 12 kids compared to 10. Bonus: 45 pairs of twins.

As Staff Writer, Derek strives to bring you exciting Bedtime Math content and keep commas in their rightful place. Previously he helped manage a film studio in the Philadelphia area. Derek holds a B.A. in Communication- Media Production from Villanova University.