Equivalent Rational Number to 9/10 with 90 as Numerator
To find a rational number equivalent to 9/10 with 90 as the numerator, we need to first understand the concept of equivalent fractions. Equivalent fractions are fractions that have the same value but different numerators and denominators.

Step 1: Determine the Equivalent Fraction
To find an equivalent fraction to 9/10 with 90 as the numerator, we can use the formula:
New Numerator = (Given Numerator * New Denominator) / Given Denominator
New Numerator = (9 * 90) / 10
New Numerator = 810 / 10
New Numerator = 81
So, the equivalent fraction to 9/10 with 90 as the numerator is 81/90.

Step 2: Simplify the Equivalent Fraction
To simplify the fraction 81/90, we can find the greatest common divisor (GCD) of the numerator and denominator, which is 9. Divide both the numerator and denominator by the GCD to get the simplified fraction:
81 ÷ 9 = 9
90 ÷ 9 = 10
Therefore, the simplified form of the equivalent fraction 81/90 is 9/10.

Conclusion
By following the steps mentioned above, we have found a rational number equivalent to 9/10 with 90 as the numerator. The equivalent fraction is 81/90, which simplifies to 9/10.