+0

# Counting problem

0
50
4

How many positive integers less than 1000 have at least one digit of 0 and at least one digit of 1?

Nov 1, 2021

#1
+3

10 , 100 , 101 , 102 , 103 , 104 , 105 , 106 , 107 , 108 , 109 , 110 , 120 , 130 , 140 , 150 , 160 , 170 , 180 , 190 , 201 , 210 , 301 , 310 , 401 , 410 , 501 , 510 , 601 , 610 , 701 , 710 , 801 , 810 , 901 , 910 , 1000 , >>Total = 37 such numbers

Nov 1, 2021
#4
+390
+1

Hello Guest,

almost right, but there are 36 positive integers, less than 1000 and not equal to or larger.

Anyway, everyone makes mistakes ...

Straight

Straight  Nov 10, 2021
#3
+115335
+2

How many positive integers less than 1000 have at least one digit of 0 and at least one digit of 1?

So the digits will be

10     one of these

or

10*     10 of these

or

1*0      10 of these

take away one because you added   100  twice

* 10       where the * is between 2 and 9 inclusive .    8 of these

*01       where the * is between 2 and 9 inclusive .    8 of these

now add them up.

Guests way of just listing them was easier.

Nov 1, 2021