Let's calculate 7787 x 1580
7787 × 1580 = 1580 × (7787)
+ 1580 × 7 what gives us 11060
+ 1580 × 80 resulting in 126400
+ 1580 × 700 resulting in 1106000
+ 1580 × 7000 resulting in 11060000

= 12303460
