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⁞ Number Systems

Aptitude ➤ Number Systems ➤ 1
Question 1
Q1.  The smallest prime number is ?
 

Answer :  2


The smallest prime number is 2.
⚔ DISCUSS

Question 2
Q2.  What is the unit digit in the product (114 X 859 X 213 X 476) ?
 

Answer :  8


Unit digit in the given product
= Unit digit in the product (4 X 9 X 3 X 6)
= Unit digit in the product (36 X 18)
= Unit digit in the product (6 X 8)
= 8
⚔ DISCUSS

Question 3
Q3.  What is the unit digit in the product (3547)153 X (251)72 ?
 

Answer :  7


Required Unit digit = Unit digit in (7153 X 172)

Now, 74 gives unit digit 1 and 172 = 1

(7153 X 172) = [(74)38 X 7 X 1 ]

∴ Required Unit degit = (1 X 7 X 1) = 7.
⚔ DISCUSS

Question 4
Q4.  Find the unit's digit in (264)102 + (264)103 ?
 

Answer :  0


(264)102 + (264)103 = (264)102 [1 + 264] = (264)102 X 265

Required Unit digit = Unit digit in ((4)102 X 5)
= Unit digit in ((44)25 X 42 X 5)

Now , Unit digit in 44 = 6
Unit digit in 42 = 6

∴ Required Unit digit = Unit digit in (6 X 6 X 5)
= Unit digit in (36 X 5)
= Unit digit in (6 X 5)
= Unit digit in (30)
= 0.
⚔ DISCUSS

Question 5
Q5.  What least number must be added to 3000 to obtain a number exactly divisible by 19 ?
 

Answer :  2


On dividing 3000 by 19, we get 17 as remainder.

∴ Number to be added = (19 - 17) = 2.
⚔ DISCUSS

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