A binary number consists of two possible digits: 0 and 1. When using seven digits, each digit can independently be either 0 or 1. Therefore, the total number of binary numbers that can be formed with seven digits is (2^7), which equals 128. Thus, there are 128 different binary numbers that can be written using seven digits.
36
The sum of the number of digits in all the numbers between 31 and 400 inclusive is 1041.
180
I assume you mean significant digits. All digits are significant. A zero between other digits is always significant.
There are 6484 digits BETWEEN the two given numbers.
36
223
123
One million is 1 followed by 6 zeroes - a total of 7 digits.
The sum of the number of digits in all the numbers between 31 and 400 inclusive is 1041.
I believe here are 51 such numbers.
Typically one letter followed by seven numbers.
180
You have seven different digits (symbols) to choose from, so you can form seven different one digit numbers and 7×7=72=49 different two digit numbers.
There are 167960 9 digits combinations between numbers 1 and 20.
I assume you mean significant digits. All digits are significant. A zero between other digits is always significant.