Problem: Let P equal the product of 3,659,893,456,789,325,678 and 342,973,489,379,256. The number of digits in P is:
Answer Choices:
A. 36
B. 35
C. 34
D. 33
E. 32
Solution:
Let N1​ represent the first factor of P and let N2​ represent the second factor. Then (4) (10)18>N1​>(3)(10)18 and (21​)(10)15>N2​>(31​)(10)15. Therefore, (2) (10) 33>N1​N2​ >(1)(10)33 so that the number of digits in P(=N1​N2​) is 34