23% of 6783 + 57% of 8431 =?

It can be written as

23% of 6800+ 57% of 8400 =?

$=\frac{23\times 6800}{100}+\frac{57}{100}\times 8400=?$

= 23×68+57×84=?

= 23×70+60×84=?

= 1610+5040=?

= 6650≈6630

Hence, Option D is correct.