If we use numbers that can be written with only ones and zeros, then we're working with binary numbers. The largest binary number that can be written with seven bits is "127". When you remember to include 'zero', that makes a total of 128 different numbers. The sum of the (smallest + largest) is (0 + 127) = 127 The sum of the (second smallest + second largest) = (1 + 126) = 127 The sum of the (third smallest + third largest) = (2 + 125) = 127 Each sum built in this way is 127, and there are (half of 128) = 64 of them. So the sum of all 128 numbers is (64 times 127) = 8,128
1 million 1,000,000
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.
Four-digit phone numbers were primarily used in the United States before the widespread adoption of area codes and seven-digit dialing. This system was prevalent from the early 20th century until the late 1950s, when the North American Numbering Plan was introduced, requiring the use of three-digit area codes and seven-digit local numbers. The transition to seven-digit dialing became standard as more telephone lines were added and the need for more numbers grew.
Seven of them.
252
To find the total number of seven-digit numbers that contain the number seven at least once, we can use the principle of complementary counting. There are a total of 9,999,999 seven-digit numbers in total. To find the number of seven-digit numbers that do not contain the number seven, we can count the number of choices for each digit (excluding seven), which is 9 choices for each digit. Therefore, there are 9^7 seven-digit numbers that do not contain the number seven. Subtracting this from the total number of seven-digit numbers gives us the number of seven-digit numbers that contain the number seven at least once.
1 million 1,000,000
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.
420 and 840
In the 1940s, phone numbers typically consisted of a three-digit area code followed by a seven-digit local number, such as "ABC-1234." This format differed from modern phone numbers, which generally have a three-digit area code followed by a seven-digit local number, such as "(123) 456-7890."
Seven of them.
252
A 75 hp Mercury outboard, serial number OB9655687, I can not find on the serial number chart. One thing I see, is a seven digit serial number, with a OB prefix. The seven digit serial numbers, ( prior to 1985 ), had no prefix. Serial numbers with the prefix, ( OA,OB,OC, ect. ), have six digit serial numbers. Could there be an error in the serial number posted?
That makes:* 8 options for the first digit * 8 options for second digit * 10 options for the third digit * ... etc. Just multiply all the numbers together.
9,000,0009,999,999 is the last 7 digit number1,000,000 is the first 7 digit numberwhen you subtract the first from the last and add one you get the above answer.
Same as the odd numbers anywhere else, except the first digit is always "7"
you say one number first then the other one for example 789 you say seven eight and then nine