Using add subtract multiply and divide, how do 4 9s equal 90

To make 90 using exactly four 9s with the operations of addition, subtraction, multiplication, and division, you can use the following expression:

\[ 99 - \frac{9}{9} = 90 \]

Here's how it works step-by-step:

1. **Create 99 using two 9s:** \( 99 \)
   - You can form 99 by combining two 9s: 9 followed by 9 gives you 99.

2. **Divide 9 by 9 to get 1:** \( \frac{9}{9} = 1 \)
   - Using the remaining two 9s, you can divide one by the other, resulting in 1.

3. **Subtract 1 from 99:** \( 99 - 1 = 90 \)
   - Finally, subtract the result of the division (1) from 99 to get 90.

Thus, using the four 9s with the allowed operations, \( 99 - \frac{9}{9} \) gives you 90.

Would you like more details or have any questions about this solution? Here are some related questions to think about:

1. How can you express the number 100 using four 9s?
2. Can you find a way to make 91 using four 9s?
3. How many ways can you make the number 10 using four 9s?
4. Can you use four 9s to create a number less than 50?
5. What other numbers can you create using four 9s and basic arithmetic operations?

**Tip:** When solving these types of puzzles, remember that combining digits (like forming 99 from two 9s) and using parentheses can help you reach the desired result creatively.

Discover how to use exactly four 9s to create the number 90 through addition, subtraction, multiplication, and division. This math problem explores basic arithmetic operations and creative number formation. Suitable for students in Grades 4-6.

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