Brain Teasers
What's in a Number?
Complete the sequence:
21, 13, 24, 26, ??
21, 13, 24, 26, ??
Hint
Who needs the decimal system? Sometimes numbers are just slapped together!Answer
48The first digit of each number is the absolute value of the result of subtracting the preceding number's digits from each other (|2-6|=4), and the second number is the sum of the preceding number's digits (2+6=8).
Hide Hint Show Hint Hide Answer Show Answer
What Next?
View a Similar Brain Teaser...
If you become a registered user you can vote on this brain teaser, keep track of which ones you have seen, and even make your own.
Solve a Puzzle
Comments
huh?? I dont speek math
i think it is hard to figure out with just the 4 examples. maybe add a couple more numbers to the series.
21, 13, 24, 26, 48, 412, ??
It is not possible to add a couple more terms for clarity. The next term after 48 has three digits. You can derive a sum from that, but what is the difference of three numbers? The rule is ambiguous for the second digit.
Otherwise, it is a clever finite series. I didn't have the patience to figure it out.
It is not possible to add a couple more terms for clarity. The next term after 48 has three digits. You can derive a sum from that, but what is the difference of three numbers? The rule is ambiguous for the second digit.
Otherwise, it is a clever finite series. I didn't have the patience to figure it out.
If you had a million monkeys pounding on a million calculators you would have a fair description of me trying to figure this out.
Very nice
To post a comment, please create an account and sign in.
Follow Braingle!