saswata4s wrote:
If 10^15 – 49 is written as an integer in base 10 notation, what is the product of digits in that integer?
A) 9^13
B) 4* 9^13
C) 5 * 9^13
D) 51* 9^13
E) 5 * 9^14
Let's look for patter
100 - 49 = 51
1000- 49 = 951
10000 -49 =9951
100,000 - 49 = 99951
Notice that it is 9 is always less than number of Zero by 2.
We have 15 zero's, so we get 13 of 9's........9 ^13
Also 5 *1 =5
So finally we get: 5 *9^13
Answer: C
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