No problem, we've got 4057 and 7800 to multiply
4057 × 7800 = 7800 × (4057)
+ 7800 × 7 giving us 54600
+ 7800 × 50 what gives us 390000
+ 7800 × 000 which equals 0
+ 7800 × 4000 what gives us 31200000

= 31644600
