No problem, we've got 20148479 and 15665578 to multiply
20148479 × 15665578 = 15665578 × (20148479)
+ 15665578 × 9 that is equal 140990202
+ 15665578 × 70 what gives us 1096590460
+ 15665578 × 400 that results in 6266231200
+ 15665578 × 8000 resulting in 125324624000
+ 15665578 × 40000 that is equal 626623120000
+ 15665578 × 100000 yielding 1566557800000
+ 15665578 × 0000000 which equals 0
+ 15665578 × 20000000 yielding 313311560000000

= 315637569355862
