Multi-Credits applied to a race with a low Credits reward: 61 times 
408 would have given less than 25,000, so the factor is 62.
Multi-Credits is a bonus in Asphalt 8: Airborne which was introduced with the Sixth Anniversary Update and can be obtained three times per day by watching an ad after a race. The ad option is not displayed if a 
Double Credits booster is active.
The Multi-Credits ad bonus replaces the Double Credits ad bonus and works in a similar fashion, but instead of factor 2, the rewarded Credits are multiplied with the smallest integer factor such that the result is greater than or equal to a defined threshold.
The threshold depends on the player's earned career 
Stars; for advanced players, it is limited to 25,000. The amount of rewarded Credits earrned in the race is irrelevant—the smaller the amount of Credits, the greater the factor.
This means that players now don't have to choose races with high Credit rewards for the bonus as they can be sure that the bonus will be greater than or equal to the threshold. However, there can still be considerable differences. Given a threshold of 25,000,
Example for a high Credits reward and a small factor, leading to a bonus greater than 25,000
- a
5,000 reward would be multiplied with 5 to give a 25,000 bonus. - A 6,240 reward would also lead to a factor of 5 because 4 times 6,240 would be less than the threshold ( 24.960). Hence, the player would get 5 times 6,240 = 31,200.