Find four positive integers a, b, c, and d such that the product abcd is equal to the sum of the squares, a2 + b2 + c2 + d2.
abcd = a2 + b2 + c2 + d2
What? That’s too easy, you say? You’re probably right. But can you find four different solutions —
· One that uses the same number four times?
· One that uses the same number three times?
· One that uses the same number twice?
· And, one that uses four different numbers?
This brainteaser was written by Derrick Niederman.
Problem and solution
Find four positive integers a, b, c, and d such that the product abcd is equal to the sum of the squares, a2 + b2 + c2 + d2.
abcd = a2 + b2 + c2 + d2
What? That’s too easy, you say? You’re probably right. But can you find four different solutions —
· One that uses the same number four times?
· One that uses the same number three times?
· One that uses the same number twice?
· And, one that uses four different numbers?
This brainteaser was written by Derrick Niederman.
Problem and solution
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