According to the meaning of the question, there are 8 splits in 4 hours and 12 splits in 6 hours; We analyze it through the division of a single bacterium:

Beginning: The number of bacteria is 1, which is the zeroth power of 2.

The first division: the number of bacteria is 2, which is 2.

The second division: the number of bacteria is 2 to the second power, which is 4.

..... and so on, one eighth, the number of bacteria is two to the eighth power, which is 256.

But in the next division, 12.5% of the bacteria will die, 12.5%= 1/8.

Let's use chart analysis.

Bacteria divide 12 times in 6 hours, that is, 12 to the fourth power (7/8), that is, 240 1.

In the later division, you will calculate decimals and directly omit the small trees for rounding. For example, calculate 13 splits.

357 1.75 bacteria, rounded to 357 1 bacteria.

The answer to the second question has been given on the road, m refers to the number, n refers to the split fraction, remember n≧8.