Discussion

Explanation:

Let’s look at the last digit of powers of 8.

81 = 8,
82 = 4,
83 = 2,
84 = 6, 
85 = 8, 
86 = 4,
87 = 2,
88 = 6,
… 

Thus, it can be seen that the unit’s digit of 8n is repeating after every 4 terms in the pattern of 8, 4, 2 and 6. 

Hence, last digit of 84n+a will be same as the last digit of 8a.

i.e., to find the last digit, divide the required power by 4 and find the remainder. 

So, when 2500 is divided by 4, it gives 0 as the remainder. Therefore, the last digit of 82500 is same as the last digit of 84 = 6.

Hence, option (b).

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