Medical Quiz in Mathematical Form

We were told since our Childhood that we are born with specific number of Brain cells (Neurons) and Our Brain can't generate new ones. But thanks to modern Science, now it's proved that we do create new neurons throughout lifetime though only in Limited areas of Brain like Hippocampus - The memory center.

This process is termed as "Neurogenesis ".

Fortunately, we can increase the process of Neurogenesis ( Neurons Birth) through,

*Physical Exercise.

*Mental Stimulation/ engaging in Learning.

*Right Diet, to name a few.

Unfortunately, This process of Neurogenesis is reduced dramatically as we get older causing Memory loss and Cognitive decline.

Neurogenesis is also believed to be permanently reduced in someone who had survived Bacterial Meningitis in childhood.

Third major cause of Reduction in Neurogenesis is Stress, Anxiety or Severe Depression (Reversible when Depression is treated).

Neurogenesis is also reduced in those who drink Alcohol heavily.

Imagine, an average normal Human Brain creates 1500 new Neurons per day. And following factors increase Neurogenesis,

Physical Exercise ( 3 folds)

Mental Stimulation (2 folds)

while the following factors reduce Neurogenesis,

Old age over 60y (30 folds approx.)

Bacterial Meningitis (7 folds)

Stress/Depression (3 folds)

Assuming a linear relation, How many Neurons an old man is estimated to generate, who unfortunately, survived Childhood Bacterial Meningitis and exercises regularly? ? (Note: if answer comes out in decimal form then round it to the next number e.g 1.2 as 2.)