please help

$3.54\times105+6.3\times104$

$371.7+6.3\times104$

$371.7+665.2$

$1026.9$

$1.0269\times{10}^{3}$

I think this might be :

3.54 * 10⁵  * 6.3 * 10⁴        which we can reorder as  :

3.54 * 6.3 * 10⁵ * 10⁴    =

22.302 * 10⁹  =

2.2302 * 10¹⁰