Gram of TNT = 4184 Joules
Kilogram of TNT = 1000 grams = 4184000 Joules
Ton of TNT = 4184000000 Joules
Kiloton = 1000 Tons of TNT = 4.184 * 10^9 Joules
Megaton = 10^6 Tons of TNT = 4.184 * 10^12 Joules
Gigaton = 10^9 Tons of TNT = 4.184 * 10^15 Joules
Teraton = 10^12 Tons of TNT = 4.184 * 10^18 Joules
Petaton = 10^15 Tons of TNT = 4.184 * 10^21 Joules
Exaton = 10^18 Tons of TNT = 4.184 * 10^24 Joules
Zettaton = 10^21 Tons of TNT = 4.184 * 10^27 Joules
Yottaton = 10^24 Tons of TNT = 4.184 * 10^30 Joules
Ninaton = 10^27 Tons of TNT = 4.184 * 10^33 Joules
Tenaton = 10^30 Tons of TNT = 4.184 * 10^36 Joules
Kilotenaton = 10^33 Tons of TNT = 4.184 * 10^39 Joules
Foe = 23.900573613767 Kilotenatons = 2.3900573613767 * 10^34 Tons of TNT = 10^44 Joules
Then from their, you can use Kilo, Mega, Giga, ect with each being 10*3 more than the last, then when you get to Tena there's Kilotena, Megatena, Gigatena, ect. Then there's Tenatena, Kilotenatena, and the list goes on.