Answer:
2800
Step-by-step explanation:
We have been given that Rico is estimating [tex]138\times 18[/tex]. We are asked to find Rico's mistake.
We can see that Rico has rounded down 139 to 100 and 18 to 10.
Instead of rounding down the numbers, Rico should round up the numbers as ones place is greater than 5:
[tex]140\times 20[/tex]
[tex]2800[/tex]
Therefore, the estimated product of the given numbers would be 2800.
