Question

How many four-digit whole numbers contain the digit pair "17" without other intervening digits? (Note that 2017 is one such example but 2107 is not.)

Answer 1

Answer:

There are 209 4-digit nu numbers with 17 as consecutive digits

Step-by-step explanation:

17xx xx represent 00 through 99, a set of {100} members.

y17z. y can be 1 through 9 {9}. z can be 0 thru 9 {10}

ww17 which includes 10 thru 99, a set of {90}

Add 100+90+10+9 to get 209 possible combinations.