Question

HOW MANY 7 DIGIT TELEPHONE NUMBERS ARE POSSIBLE IF THE FIRST DIGIT CANT BE ZERO AND MUST BE MUTIPLE OF 100

Answer 1

In the image above you have the possible digits in each 7-digit position (As the first digit cannot be 0 the digts go from 1 to 9, the next 4 digits can go from 0 to 9 and the last two digits need to be 0 as it is multiple of 100). To find the amount of 7 digit telephone numbers possible you multiply the number of possible digits in each position (in red):

`9*10*10*10*10*1*1=90,000`Then, there are 90,000 possible 7 digitm telephone numbers with the given conditions