Sol : Option C
100 -87 = 13, 100 -93 = 7
13 * 7 = 91 (last two digits)
93-13= 87-7 = 80
Therefore, the correct answer is 8091
Q.3. 89 * 109
A. 9081
B. 9281
C. 9701
D. 9401
Sol : Option C
100 -89 = 11, 100 -109 = -9
11 * -9 = -99 (100-99=01) (last two digits) (1 borrowed)
109-11-= 89+9 =98 -1 (borrowed) = 97
Therefore, the correct answer is 9701
Q.4. 47 * 44
A. 2018
B. 2048
C. 2028
D. 2068
Sol : Option D
“In this case, we can take 50, which is a sub multiple of 100 or a multiple of 10 and proceed as follows:
50 -47 = 3, 50 -44 = 6
3 × 6 = 18 (last two digits)
47-6= 44 – 3= 41/2 = 20.5
= 20.5 × 100 =2050+18 =2068
Since 50 = 100/2, we divide the left hand side number also by 2 while retaining the right hand side. Therefore, the answer will be 2068.” Hence option D
Sol : Option B
(112) 2 = 112 + 12 | (12) 2 = 144 | (carry 4)44 = 12544
Q.7. 51 * 27
A. 1477
B. 1277
C. 1377
D. 1777
Sol : Option C
51
27
Step 1: 1 * 7 = 07 (Write 07).
Step 2: 1 × 2 + 5 × 7 = 37 (Write 7 and 3 is carried over to the next step)
Step 3: 5 * 2 + 3 (Carried Over) = 13 (Write 13 because this is the last step)
1377 is the answer.
Sol : Option B
72
47
Step 1: 2 * 7 = 14 (Write 4 and 1 is carried over to the next step)
Step 2: 7 * 7 + 2 × 4 + 1 (Carried Over) = 58 (Write 8 and 5 is carried over to the next step)
Step 3: 7 * 4 + 5 (Carried Over) = 33 (Write 27 because this is the last step)
3384 is the answer.
Q9. 62 * 43
A. 2566
B. 2466
C. 2866
D. 2666
Sol : Option D
62
43
Step 1: 2 * 3 = 6 (Write 6 which is the single digit number)
Step 2: 6 * 3 + 2 * 4 = 26 (Write 6 and 2 is carried over to the next step)
Step 3: 6 * 4 + 2 (Carried Over) = 26 (Write 26 as this is the last step).
2666 is the answer.