Example:
15 MeV = 2.277856e-15 Btu (IT), Btu
1 MeV = 1.51857e-16 Btu (IT), Btu | 1 Btu (IT), Btu = 6.585141e+15 MeV
Conversion Steps:
15 × (1.602177e-13 / 1055.05585262) = 2.277856e-15