Alright, let's work through 5826 times 668 step by step
5826 × 668 = 668 × (5826)
+ 668 × 6 giving us 4008
+ 668 × 20 that is equal 13360
+ 668 × 800 which equals 534400
+ 668 × 5000 that equals 3340000

= 3891768
