500
Chat with our AI personalities
256 unless you count zero in which case its 625.
To find the even two-digit numbers where the sum of the digits is 5, we need to consider the possible combinations of digits. The digits that sum up to 5 are (1,4) and (2,3). For the numbers to be even, the units digit must be 4, so the possible numbers are 14 and 34. Therefore, there are 2 even two-digit numbers where the sum of the digits is 5.
There are 5760 such numbers.
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.
The sum of the digits in odd position minus the sum of the digits in even position is divisible by 11.