Question

1. sarah bought 2.4 kg of flour. each kilogram costs $3.50. which expression and result is correct?

2.4×3.5 = 8.4
2.4×3.5 = 7.9
3.5×2.4 = 9.4
3.5×2.4 = 8.0

Explanation:

Step1: Multiply quantity and price

$2.4\times3.5$
We can calculate $24\times35 = 840$. Since there is one - digit after the decimal point in 2.4 and one - digit after the decimal point in 3.5, the product should have two digits after the decimal point. So $2.4\times3.5=8.4$. Also, multiplication is commutative, so $3.5\times2.4 = 2.4\times3.5=8.4$.

Answer:

$2.4\times3.5 = 8.4$ (the first option is correct)