22.5L is needed for one month. 6 containers should be ordered. 1.5L of chlorine will be left at the end of the month.
Work Step by Step
Multiply to find the amount of chlorine needed for 30 days. $750mL\times30=22,500mL$ Move the decimal to convert mL to L. $22,500mL=22.5L$ Divide to find the number of 4L containers. Round up to ensure the chlorine does not run out. $22.5\div4=5.625\approx6$ Multiply to find the total amount in the 6 containers. $4L\times6=24L$ Subtract to find how much is left over. $24L-22.5L=1.5L