The sugar company produced 6,236,854,265 sugar cubes last month. This month the company produced 7,771,635,486 sugar cubes. What number sentence best represents how to find the total estimate of sugar cubes produced?
A. 6,000,000,000 + 7,000,000,000
B. 6,000,000,000 + 8,000,000,000
C. 7,000,000,000 + 7,000,000,000
D. 7,000,000,000 + 8,000,000,000