No problem, we've got 7881 and 9840 to multiply
7881 × 9840 = 9840 × (7881)
+ 9840 × 1 which equals 9840
+ 9840 × 80 what gives us 787200
+ 9840 × 800 which equals 7872000
+ 9840 × 7000 that results in 68880000

= 77549040
