Problems based on Numbers Test 2

Question : 15 of 40

Marks: +1, -0

The last digit, that is, the digit in the unit’s place of the number

[(57)^25 - 1]

is:

Solution:

To find the unit digit of

(57)^25

Unit digit of

7^1=7

7^2=9

7^3=3

7^4=1

7^5=7

So,

57^{6×4}×57^1=7

∴ the unit digit of

[(57)^25 - 1]

=7-1=6

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