Q643
What is the value of 9991 × 10009?
A.
99999099
B.
99999819
C.
99999919
AnswerD.
99999019
Answer: Option C
Solution
Answer: Option C
Solution:
9991 × 10009= 9991(10000 + 9)
= 99910000 + 89919
= 99999919
Alternate solution
9991 × 10009
= (10000 - 9)(10000 + 9)
= (10000)2 - (9)2
= 100000000 - 81
= 99999919