Example:
15 Btu (th) = 1.581525e+10 µJ
1 Btu (th) = 1.05435e+9 µJ | 1 µJ = 9.484517e-10 Btu (th)
Conversion Steps:
15 × (1054.349999974 / 0.000001) = 1.581525e+10