1. What could be the units digit of 22n, where n is an integer.
A.1
B.2
C.3
D.4
E.5
F.6
G.8
2. Find the units digit of 4342
A.0
B. 2
C.4
D. 6
E. 8
3. What is the unit digit of 11x22X33 X.......99?
A. 0
B. 1
C. 2
D. 3
E. 5
4. What could be the units digit of 19473n
A.0
B.1
C.2
D.3
E.6
F.8
G.9
5.What is the unit digit of 93n+5, n is a prime number greater than 5.
6.Find the units digit of 10011+10022+10033+.......10099?
A.0
B. 1
C. 2
D. 3
E. 7
7. What could be the units digit of 9nX 22n, where n is an integer?
A.2
B.3
C.6
D.11
E.13
F.15
G.17
8.Find the units digit of 11X33X55X77X.......9797X9999
A. 0
B. 1
C. 2
D. 3
E. 5
9. abcd is a four digit number. Find the value of d if the units digit of (abcd)15 is 6
A. 2
B. 4
C. 6
D. 8
E. 9
10. abcd is a four digit number. What could be the value of d if the units digit of (abcd)12 is 6
A. 1
B. 2
C. 4
D. 6
E. 8
F. 9
11. 172271 has a units digit of:
12.a,b are single digit positive integers. If the units digit of ab+ba=6,then find the value of (a+b).
A. 6
B. 8
C. 10
D. 12
E. 14
13.11+22+33+...+100100 is divided by 2. What is the remainder?
A. 0
B. 1
C.2
D. 3
E. 4
14.What is the units digit of (71)5(46)3(103)4 + (57)(1088)3 ?
A. 0
B. 1
C. 2
D. 3
E. 4
15. What is the units digit of 17728 – 13323?
A. 1
B. 3
C. 4
D. 6
E. 9
16. If a,b are two positive integers which of the following must be true.
A. 5a+6b is even
B. 8a+6b is odd
C. 5a+7b is odd
D. 7a+6b is divisible by2.
E. 5a+6b is odd.
17.How many zeroes does 20020 have?
A. 40
B. 48
C. 49
D. 51
E. 54
18. What is the first non-zero digit that the number 20020has from the right?
A. 0
B. 1
C. 2
D. 3
E. 6
19. What is the units digit of 292008-181996?
A. 0
B. 3
C. 5
D. 11
E. 13
20.What is the units digit of 292008+181996?
A. 6
B. 7
C. 9
D. 12
E. 15
Explanation for Question1:
What could be the units digit of 22n, where n is an integer.
Answer – (C)
Solution:
22n is nothing but 2even 2even ends with either 4 or 6.
Find the units digit of 4342
Answer – (C)
Solution:
4342 is nothing but 4odd. 4odd always ends with 4.
What is the unit digit of 11x22X33 X.......99
Answer – (A)
Solution:
11x22X33 X.......99 consists 55 55 ends with 5. Multiples of 5 either end with 0 or 5. 5 multipled with even numeber always end with zero. So the answer is 0.
Explanation for Question 4:
What could be the units digit of 19473n
Solution: the units digit of 19473n is same as the units digit of 73n when n=1, the units digit of 73=3
when n=2, the units digit of 76=9
when n=3, the units digit of 79=7
when n=4, the units digit of 712=1
5.What is the unit digit of 93n+5, n is a prime number greater than 5..
Answer:6 Solution: Any prime number greater than 5 is always odd. therefore 3n is odd 3n+5 is even. 93n+5=9even,which always ends with 1.
Explanation for Question 6:
.Find the units digit of 10011+10022+10033+.......10099?
Answer – The units digit of11=1 The units digit of22=4 The units digit of33=7 The units digit of44=6 The units digit of55=5 The units digit of66=6 The units digit of77=3 The units digit of88=6 The units digit of99=9 Sum of the units digit =47
Explanation for Question 7:
What could be the units digit of 9nX 22n, where n is an integer?
Answer :By plugging n=1,2,3...in 9nX 22n,it always ends with 6.
Explanation for Question8:
Find the units digit of 11X33X55X77X.......9797X9999
Answer:55 ends with 5. Multiples of 5 either end with 0 or 5. 5 multipled with odd numeber always end with 5. So the answer is 5.
Explanation for Question9:
abcd is a four digit number. Find the value of d if the units digit of (abcd)15 is 6?
Answer-by verifying the options d= 6 satisfies. so the answer is 6.
Explanation for Question 10: abcd is a four digit number. What could be the value of d if the units digit of (abcd)12 is 6 Solution:By verifying the optios d=2,4,6,8 satisfies.
Explanation for Question 11:
172271 has a units digit of:
Answer – 8 Solution: the units digit of 172271 is equal to 2271 2271 is in the form of 24n+3,which end with 8.So the answer is 8.
Explanation for Question 12:
a,b are single digit positive integers. If the units digit of ab+ba=6,then find the value of (a+b).
. Solution: The only combination satisfies is 5,1. Hence the answer is 6.
Explanation for Question 13:11+22+33+...+100100 is divided by 2. What is the remainder? Explanatory Answer 11+22+33+...+100100 is even. When even number is divided by 2 it leaves a remainder 0.
Explanation for Question 14:What is the units digit of (71)5(46)3(103)4 + (57)(1088)3 Explanatory Answer The units digit of 715=7 The units digit of 463=6 The units digit of 1034=1 The units digit of(71)5(46)3(103)4 = 1 x 6 x 1=6---------> (i) The units digit of 10883=2 The units digit of (57)(1088)3= 7 x 2 =4---------->(ii) adding (i) and (ii) the answer is 0.
Explanation for Question 15 What is the units digit of 17728 – 13323?
Explanatory Answer
the units digit of 17728=1 the units digit of 13323=7 1-7=4 ( 17728 is greater than 13323)
Explanation for Question 16: If a,b are two positive integers which of the following must be true. Solution:A:
A. 5a+6b is even :5a is odd,6b is even odd+even=odd, option A is ruled out.
B. 8a+6b is odd:8a is even,6b is even even+even=even, option B is ruled out.
C. 5a+7b is odd:5a is odd,7b is odd odd+odd=even, option C is ruled out.
D. 7a+6b is divisible by2.:7a is odd,6b is even odd+even=odd, which is not divisible by 2.
E. 5a+6b is odd. 5a is odd,6b is even odd+even=odd, option E is the correct.
Explanation for Question 17:
How many zeroes does 20020 have?
Explanatory Answer
20020=220x10020 10020 ends with 40 zeroes.
Explanation for Question 18: What is the first non-zero digit that the number 20020has from the right? Explaination: 20020=220x10020 220 ends with 6. the first non-zero digit in 20020 is 6.
Explanation for Question 19: What is the units digit of 292008-181996 Explaination:the units digit of 292008=1 the units digit of181996 is 6. 292008 is greater than 181996 11-6=5(1 carring 1 from the prevous digit 1 will become 11)
Explanation for Question 20: What is the units digit of 292008-181996 Explaination:the units digit of 292008=1 the units digit of181996 is 6. 292008 is greater than 181996 1+6=7.