Why do you have to use estimation to find the number of triangles you need

for the string?

4 answers

Because its easier....??
what string?

and certainly, estimation is often easier than detailed calculation.
We used estimating to find the total number of flags/pennants because estimating leaves us with a whole number. We cannot use detailed calculations because we would end up with a decimal, therefore we would not be able to make a flag based off of a decimal.
lol this dude is smart