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Match List-I with List-II

List-IList-II
(A) Unit's digit of (257)153×(346)72(257)^{153} \times (346)^{72}(I) 3
(B) Unit's place of the product 61×62×63×64×...×6961 \times 62 \times 63 \times 64 \times ... \times 69 is(II) 4
(C) 121012 is divided by 12, the remainder is(III) 0
(D) Unit's digit of (257)153+(346)72(257)^{153} + (346)^{72}(IV) 2

Choose the correct answer from the options given below:

Solution

✅ Correct Option: 2

Finding the unit's digit of (257)153×(346)72(257)^{153} \times (346)^{72}:

For multiplication, find the unit's digit of each number separately, then multiply them.

Unit's digit of 257 is 7. Finding the pattern when multiplying 7 repeatedly:

71=77^1 = 7 (unit's digit: 7)

72=497^2 = 49 (unit's digit: 9)

73=3437^3 = 343 (unit's digit: 3)

74=24017^4 = 2401 (unit's digit: 1)

75=168077^5 = 16807 (unit's digit: 7)

Pattern: {7, 9, 3, 1} repeats every 4 powers.

Dividing the exponent: 153÷4=38153 \div 4 = 38 remainder 11

Remainder 1 corresponds to position 1 in pattern: 7

Unit's digit of 346 is 6. Any power of 6 always ends in 6.

Multiplying the unit's digits:

7×6=427 \times 6 = 42

Unit's digit = 2

(A) → (IV)


Finding the unit's place of 61×62×63×64×...×6961 \times 62 \times 63 \times 64 \times ... \times 69:

To get unit's digit 0, the product needs both 2 and 5 as factors.

65=5×1365 = 5 \times 13 (provides factor 5)

64=2664 = 2^6 (provides factors of 2)

Since both are in the product: 2×5=102 \times 5 = 10

Any number with 10 as a factor has unit's digit 0.

(B) → (III)


Finding the remainder when 121012 is divided by 12:

Breaking down 121012:

12×10000=12000012 \times 10000 = 120000

121012−120000=1012121012 - 120000 = 1012

Dividing 1012 by 12:

12×84=100812 \times 84 = 1008

1012−1008=41012 - 1008 = 4

Remainder = 4

(C) → (II)


Finding the unit's digit of (257)153+(346)72(257)^{153} + (346)^{72}:

From the earlier calculations:

Unit's digit of (257)153=7(257)^{153} = 7

Unit's digit of (346)72=6(346)^{72} = 6

Adding the unit's digits:

7+6=137 + 6 = 13

Unit's digit = 3

(D) → (I)


Final Matching:

(A) → (IV) = 2

(B) → (III) = 0

(C) → (II) = 4

(D) → (I) = 3

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