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>N1N2 >(1)(10)33 so that the number of digits in P(=N1N2) is 34