Question

Estimate product
126.12 and 2.2

Answer 1

I might round 126.12 UP to 130 and 2.2 DOWN to 2, then multiply 130 x 2 to get 260. This UNDER-estimates the true answer, 277.4, because rounding 126.12 up to 130 is only a slight increase percentage-wise (about 3%) whereas rounding 2.2 down to 2 is a greater decrease percentage-wise (10%).

Answer 2

so estimate
round to whole numbers
126 times 2
we know that times 2 is just add them twice
126 times 2=126+126=252
aprox 252