1 point We usually write numbers in decimal form or base 10 meaning numbers are composed using 10 different digits 0 1 9 Sometimes though it is useful to write numbers hexadecimal or base 16 Now there are 16 distinct digits that can be used to form numbers 0 1 9 A B C D E F So for example a 3 digit hexadecimal number might be 2B8 a How many 3 digit hexadecimals are there in which the first digit is E or F b How many 6 digit hexadecimals start with a letter A F and end with a numeral 0 9 c How many 4 digit hexadecimals start with a letter A F or end with a numeral 0 9 or both