No problem, we've got 81721525 and 66398276 to multiply
81721525 × 66398276 = 66398276 × (81721525)
+ 66398276 × 5 that results in 331991380
+ 66398276 × 20 what gives us 1327965520
+ 66398276 × 500 giving us 33199138000
+ 66398276 × 1000 which equals 66398276000
+ 66398276 × 20000 that results in 1327965520000
+ 66398276 × 700000 resulting in 46478793200000
+ 66398276 × 1000000 resulting in 66398276000000
+ 66398276 × 80000000 that equals 5311862080000000

= 5426168372090900
