If you mean, "What is the largest number of digits possible in the product of two 2-digit numbers" then 99 * 99 = 9801, or 4 digits. Anything down to 59 * 17 = 1003 will have 4 digits.
from 3 digits (10x10) to 4 digits (99X99)
-21
144
To find the fraction of 4-digit natural numbers with a product of their digits that is even, we first need to determine the total number of 4-digit natural numbers. There are 9000 such numbers (from 1000 to 9999). Next, we consider the conditions for the product of digits to be even. For a number to have an even product of digits, at least one of the digits must be even. There are 5 even digits (0, 2, 4, 6, 8) and 5 odd digits (1, 3, 5, 7, 9). Therefore, the fraction of 4-digit natural numbers with an even product of digits is 5/10 * 9/10 * 9/10 * 9/10 = 3645/9000 = 809/2000.
two
231
22
420
If you mean, "What is the largest number of digits possible in the product of two 2-digit numbers" then 99 * 99 = 9801, or 4 digits. Anything down to 59 * 17 = 1003 will have 4 digits.
231
If they are multiples of 9, the digits add up to a multiple of 9.
from 3 digits (10x10) to 4 digits (99X99)
You had me until "product." The product of 4 digits can't be prime.
15 or 35
Zero.
There are two numbers that satisfy the criteria. 38 and 83