Visa cards have 16 digits. The first digit is always 4 as in 4xxxxx – with the 2nd to 6th digits being the bank number while the 7th-15th numbers are your account number. The final digit is the check digit.   How many possible Visa card numbers are available?

How many times did you write the digit 4 if you write down all the numbers from 1 to a million?

Why do you put a "1" in front of 9, 26, and 10?

On September 9th, a student in Bill Nye's science class answered one chemistry question. Each day after that, the student answered 8 more chemistry questions than the day before. By the end of class on September 30th, how many chemistry questions had the student answered?

what would it be for 15 or older?

Ernie wrote 10 checks last month and these were the only transactions for his checking account. According to his check register, his balance is $1884.88, but the bank statement he just received says his balance is $2117.29. If nine of Ernie's 10 checks have cleared, what is the amount of the check that hasn'tyet cleared?

what two numbers are added together to give 12 but multiplied to give -16?

Mr. Imperfecto teaches another math class.  This time he has 23 students take a test, the average score on which is an 87.  Mr. Imperfecto realizes he put the wrong grade in for a student.  He entered a 35, and the score should have been an 85.  To the nearest integer, what is the new class average?

In the mid 1990 the state of Florida ran out of the combination of letters and numbers for license plates. Then, each license plate contained 3 letters of the alphabet followed by 3 digit from 0-10. How many combinations are there?