# Quiz - 3¶

We say that a natural number is triangular if it is the product of three consecutive natural numbers.

Example: 120 is triangular, since 4 x 5 x 6 = 120. Given a non-negative integer `n`, check if `n` is triangular. Return `True` if the number is triangular or `False` if it is not.

Indicate how to make change using the minimum number of bills. Your algorithm should read the amount of the bill to be paid, `cobro`, and the amount paid, `pago`, without taking into account the cents.
Suppose the bills for change are 50, 20, 10, 5, 2 and 1, and that none of them is missing in the cash register. Return a list with the quantity of each bill that represents the change.
The first element of the list matches the quantity of 50, the next with 20, and so on until 1. (The same order as shown above).

Examples:
`calculate_change(50, 100)` -> [1,0,0,0,0,0]
`calculate_change(92, 100)` -> [0,0,0,1,1,1]

Check whether a positive integer `n` is prime.
Return `True` if it is prime or `False` if it is not.

Given a positive integer `n`, determine its prime factorization also calculating the multiplicity of each factor. Return a dictionary with the keys as primes and their respective values as the frequency of the prime in the prime factorization of the number.

Examples:
`factors(5)` -> {5:1}
`factors(420)` -> {2:2, 3:1, 5:1, 7:1}

Make a program that asks for a positive integer `n` and shows it inverted. For example: 1234 generates 4321. Return the inverted number.

Examples:
`invert_number(123456789)` -> 987654321
`invert_number(1000)` -> 1