639 metric teaspoons in US customary teaspoons

Conversion formula
How to convert 639 metric teaspoons to US customary teaspoons?

We know (by definition) that: $1\mathrm{brteaspoon}\approx 1.01442068105529\mathrm{usteaspoon}$

We can set up a proportion to solve for the number of US customary teaspoons.

Now, we cross multiply to solve for our unknown $x$:

Conclusion: 639 ⁢ brteaspoon ≈ 648.2148151943303 ⁢ usteaspoon

Conversion in the opposite direction

The inverse of the conversion factor is that 1 US customary teaspoon is equal to 0.0015426984643975 times 639 metric teaspoons.

It can also be expressed as: 639 metric teaspoons is equal to $\frac{1}{\mathrm{0.0015426984643975}}$ US customary teaspoons.

Approximation

An approximate numerical result would be: six hundred and thirty-nine metric teaspoons is about six hundred and forty-eight point two one US customary teaspoons, or alternatively, a US customary teaspoon is about zero times six hundred and thirty-nine metric teaspoons.