The digit in the unit’s place of the number 7385 × 3278 is
Explanation:
The cyclicity of unit’s digit of powers of 7 is as follows:
71 = 7, 72 = 9, 73 = 3, 74 = 1, 75 = 7, 76 = 9, 77 = 3, 78 = 1, …
Dividing 385 by 4 and the remainder is 1.
Thus, the last digit of 7385 is equal to the last digit of 71 i.e. 7.
Similarly, unit’s digit of 3278 = 32 = 9.
Therefore, unit’s digit of (7385 × 3278) is unit’s digit of product of digit at unit’s place of 7385 and 3278 = 1 × 9 = 9.
Hence, 9.
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