Let's define the problem step-by-step:

1. Denominations of the Notes: Suresh has notes of denominations $1$, $5$, $10$, $20$, and $50$ rupees.
2. Equal Number of Notes for Each Denomination: Let the number of notes of each denomination be $x$.
3. Total Value of All Notes: The total amount Suresh has is $1290$ rupees.

Now, we can calculate the total value of all the notes by summing the contributions from each denomination:

$\text{Total Value} = (1 \times x) + (5 \times x) + (10 \times x) + (20 \times x) + (50 \times x)$

Simplify the expression:

$\text{Total Value} = (1 + 5 + 10 + 20 + 50) \times x = 86x$

We know the total value is Rs. 1290:

$86x = 1290$

To find $x$, solve for $x$:

$x = \frac{1290}{86} = 15$

So, Suresh has 15 notes of each denomination.

4. Total Number of Notes:

$\text{Total Number of Notes} = 5x = 5 \times 15 = 75$

Conclusion:

Suresh has a total of 75 notes.

---

Would you like more details or have any questions?
Here are some related questions that might interest you:

1. What if Suresh had different numbers of each denomination?
2. How would the answer change if Suresh had an additional denomination of Rs 100?
3. If Suresh had only Rs 640 in equal denominations, how many notes would he have?
4. How can you calculate the total number of notes for any given sum and set of denominations?
5. What are some practical applications of such problems in everyday financial management?

Tip: When dealing with word problems, always define the variables clearly and set up equations based on the relationships given in the problem.