lean_workbook_plus_471

Lastly, we oversubtracted the case where the number is divisible by all three, so we need to add this back. The product of the three prime factors is $42$ , so we have $\lfloor750/42\rfloor=17$ . Finally, we have $732-213+17=536$ numbers below 750 that are divisible by $2$ , $3$ , or $7$ .