So, recently, when I was working on my BTD5 farm analysis, I wanted to include monkey village calculations. However, I noticed that the description of a monkey village was “Monkey Village does not attack bloons but instead lowers cost of all towers and upgrades in radius by 10%. Has many useful upgrades that help nearby towers.”

However, I was playing on Hard difficulty, and I noticed that the Farm, which costs $1080 when placed in a monkey village costs me $970. Why is that? Shouldn’t it cost 90% of $1080, which is $972?

So BTD5 villages work in a weird way. On easy mode, the tower costs are 85% of normal towers. On hard mode, the tower costs are 108% of normal towers…

###### My Realization

except they’re not exactly 85% or 108%… they’re rounded to the nearest $5.

Villages when doing their calculations also round to the nearest 5. The village charges me $970 instead of $972 for a farm placed in hard mode. The 1-0 upgrade, which costs $325 should cost $292.5, but it’s also rounded down to $290. It seems that all costs are rounded **down** to the nearest 5.

To achieve this in Google Sheets, which I used, I used the rounddown() function.

=5*ROUNDDOWN(CELL*0.9/5,0). I multiplied the cost of the tower by 90% to get the 10% discount.

Here’s my BTD5 farm comparison guide.