How many Fahrenheit is 200 c?

To convert from Celsius to Fahrenheit, you use:

F = 9/5C + 32

To convert from Fahrenheit to Celsius you use:

C = (F-32) * 5/9

To convert from Celsius to Kelvin, add 273.15.

So:

200°C * 9/5 + 32 = 392 °F

200°C + 273.15 = 473.15 K

Note...

For temperatures between about -30 °(F or C) up to about 100°F, I use the formula:

F=2*C+30 or C=(F-30)/2 which I can calculate in my head.

It gives a reasonable estimate with a couple of degrees which is usually good enough, EXCEPT for calculating body temperatures and fevers. As you extend beyond normal weather temperatures, the error becomes greater.