Strong Numbers

What are Strong Numbers?

Strong number is a special number such that sum of the factorial of its digits is equal to the original number.

Strong Numbers are also known as Peterson Numbers.

Let us understand Strong Number with an example.

145 is a Strong Number.

Now,

factorial of 1 = 1! = 1

factorial of 4 = 4! = 4×3×2×1 = 24

factorial of 5 = 5! = 5×4×3×2×1 =120

sum = 1! + 4! + 5!

= 1 + 24 + 120

=145

From 1 to 1000 only the three numbers 1, 2 and 145 are Strong Numbers.

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