Problem 3 · 2009 Math Kangaroo
Easy
Number Theory
careful-counting
How many whole numbers lie between 2.009 and 23.03?
Show answer
Answer: B — 21
Show hints
Hint 1 of 2
The two endpoints are decimals, so they are not themselves whole numbers.
Still stuck? Show hint 2 →
Hint 2 of 2
Count the whole numbers strictly between 2.009 and 23.03.
Show solution
Approach: count integers in an interval
- The whole numbers lying between 2.009 and 23.03 are 3, 4, 5, …, 23.
- That list runs from 3 up to 23.
- Counting them gives 23 − 3 + 1 = 21 numbers — answer B.
Mark:
· log in to save