How many two-digit numbers are there?
Understand the Problem
The question is asking for the total count of two-digit numbers, which ranges from 10 to 99. We need to find the inclusive count of numbers in this range.
Answer
90
Answer for screen readers
The final answer is 90
Steps to Solve
- Determine the range of two-digit numbers
The two-digit numbers start at 10 and end at 99. We need to find the count of numbers from 10 to 99, inclusive.
- Use the formula for counting numbers in an inclusive range
To find the number of numbers between two inclusive limits $a$ and $b$, we use the formula $b - a + 1$.
For this problem: $$b = 99$$ $$a = 10$$ $$\text{Count} = b - a + 1$$
- Substitute the values into the formula
Substituting $a$ and $b$ into the formula: $$\text{Count} = 99 - 10 + 1$$ $$\text{Count} = 89 + 1$$ $$\text{Count} = 90$$
The final answer is 90
More Information
There are 90 two-digit numbers from 10 to 99 inclusive. Counting inclusive ranges often uses the formula $b - a + 1$.
Tips
A common mistake is to forget that the range is inclusive and not exclusive, resulting in getting 89 as the answer instead of 90.
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