Last digit of N


Here comes a grand number: N = 11986 + 21986 + 31986 + 41986.

Can you find its last digit?

 

Hint

Let’s start with 21986. Can we write it as product 
of factors whose last digits are easy to 
determine?

What number, power of 2, yields the same last 
digit when raised to any power?

It’s 16 = 24. 
16 raised to any power will give a number that 
ends in 6 (because 6 raised to any power gives a 
number that ends is 6. Always.)

Check your answer


 

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