Question

Find the area of the parallelogram 18in 13.5in 19in area = blank in squared

Answer 1

A student estimated the sum

7.95 + 8.11 + 78.5 + 8.05 + 79.4 + 0.815 as:

All the numbers begin with a 7 or 8, so use cluster estimation.

8 + 8 + 80 + 8 + 80 + 0.8 = 184.8

Explain why this reasoning is not accurate.