How to convert 664 metric teaspoons to US customary teaspoons?
We know (by definition) that:
We can set up a proportion to solve for the number of US customary teaspoons.
Now, we cross multiply to solve for our unknown :
Conversion in the opposite direction
The inverse of the conversion factor is that 1 US customary teaspoon is equal to 0.00148461493787651 times 664 metric teaspoons.
It can also be expressed as: 664 metric teaspoons is equal to US customary teaspoons.
An approximate numerical result would be: six hundred and sixty-four metric teaspoons is about six hundred and seventy-three point five eight US customary teaspoons, or alternatively, a US customary teaspoon is about zero times six hundred and sixty-four metric teaspoons.
 The precision is 15 significant digits (fourteen digits to the right of the decimal point).Results may contain small errors due to the use of floating point arithmetic.