Skip to content / Đến nội dung
ThichHocToan.com

AMO 2027 Grades 8-9 SET 9 - Self-study Question 6

AMO · AMO 2027 Grades 8-9 SET 9 - Self-study

Question 6

Say that a whole number is “five-important” if it is a multiple of 5 and/or contains the digit 5. For instance, the numbers 55, 120, and 456 are five-important, but the number 2019 is not. How many different five-important numbers are there between 1 and 2019?